Avoid using the old SplitString method in favor of the more robust
SplitPath method.

Document explicitly that the first component always exists.  Fix the
documentation of SplitPathRootComponent to note that home directory
roots (~/ and ~u/) always have a trailing slash.

See issue #11023.

Author: Clinton Stimpson <clinton@elemtech.com>

Windows paths may begin with a single backslash when the drive letter is
omitted.  Recognize this as a root path component.

Clang is smart enough to recognize that "*(int*)0=0" invokes undefined
behavior, warns, and produces an "undefined instruction".  The message
in commit "Avoid Clang optimizer bug in testProcess-[45]" (2010-07-02)
is incorrect; this is not a Clang bug.  It really is undefined
behavior.  Use "*(int*)1=0" to produce a crash instead.

Clang's optimizer, as of clang version 2.8 (trunk 107463), produces the
undefined instruction 'ud2' for the code "*(int*)0=0" on OS X x86_64.
It causes our crash tests to fail because the child process exits with
an invalid instruction instead of a segmentation fault.  Work around the
bug by using "*(int*)1=0" in this case.

Add option KWSYS_TEST_BOGUS_FAILURES that can be set by a containing
project or in the CMake cache to list tests known to fail consistently
on a buggy system.

If any of the KWSys Process tests take more than a minute or two then
something is wrong.  There is no need to wait for a long default
timeout.

Since commit "Provide unix-sytle command line parsing" (2009-07-13) the
reference to KWSYS_C_HAS_PTRDIFF_T in System.c has been meaningless
because the macro was never passed to the compiler!

Define KWSYS_DO_NOT_CLEAN_PUTENV only for the implementation.  It does
not need to be configured in the interface of "Configure.hxx".

Do not try to execute a child with no command line.  Previously this led
to a silent hang.

The DynamicLoader::LibPrefix and DynamicLoader::LibExtension methods
previously hard-coded the module name components for each platform.  Set
them from the CMAKE_SHARED_MODULE_PREFIX and CMAKE_SHARED_MODULE_SUFFIX
CMake variables instead.  This ensures consistency in a program that
uses these methods to construct the file names for its own modules.

The CopyFileIfDifferent, CopyFileAlways, CopyAFile and CopyADirectory
methods should always copy permissions.  The special cases in which a
caller would pass copyPermissions=false should be handled at the call
site.  The parameter needlessly complicates the interface and semantics
of these methods.

On Windows 7 the file size reported by 'stat' on a new file sometimes
reports zero even though the real size is correct.  This causes our
CopyFileAlways method to falsely detect copy failure.  Work around the
problem by trusting the state of ofstream after writing the file.

kFreeBSD and Hurd have the same userland as Linux.  This change is
necessary to enable kwsysProcessKill() to kill child processes on
kFreeBSD.  The bug was detected by CTestTestTimeout test.

Patch from "Modestas Vainius <modestas@vainius.eu>".
See issue #10432.

Patch from Chuck Atkins <chuck.atkins@kitware.com>

Patch from Chuck Atkins <chuck.atkins@kitware.com>

Patch to avoid short name usage where possible. Get the actual case spelling of a file name on 'Windows' without converting to short name and back again. Avoids bad behavior reported in http://bugs.winehq.org/show_bug.cgi?id=22286 when using cmake under a wine/msys/mingw installation on a Linux box. Thanks to Clinton Stimpson for preparing the patch.

Teach kwsysProcessKill to identify processes on this platform using the "ps"
command just as on Linux.  Patch from Modestas Vainius <modax@debian.org>.
See issue #10432.

In commit 'Create KWSYS_PLATFORM_INFO_TEST macro' (2009-11-20) we
implemented the macro to use a cache entry to avoid re-running the
try_compile().  However, the output copied from the try_compile is
needed on every configure.  If the user wipes out the build tree but not
the cache file then the try_compile() will not re-run to recreate the
needed file.  We address the problem by teaching the macro to run the
try_compile() whenever its output file does not exist.

This CVS keyword was copied into the file with the rest of the
implementation.  It has no meaning outside its original project tree.

COMP: remove exporting String as VS10 attempts to export its parents (basic_string) which causes all kinds of multiply defined symbols at link time.

When building on Cygwin without -mwin32, the _WIN32 macro may not be
defined.  SharedForward must still set the PATH environment variable to
ensure runtime dependencies are found.

The 'ldd' wrapping feature uses 'cygcheck' for now since a real ldd tool
is not available in Cygwin 1.5.  We can change to use the real ldd when
we choose to stop supporting legacy Cygwin and require 1.7.

Open output files with mode 0666 so that permissions are not more strict
than umask permits.  See issue #10126.

When kwsys is built using GCC visibility support can be used. This is similar
to the way that Windows exports symbols in DLLs, and requires projects that
build kwsys to change the default visibility using some compiler flags. See
http://gcc.gnu.org/wiki/Visibility for more details about GCC visibility.

The SharedForward header contains a preprocessor table mapping from
platform to equivalents for ldd and LD_LIBRARY_PATH.  This commit fixes
the table preprocessor directives to guarantee at most one platform.
This generalizes the commit "Fix compilation of VTK on debian/sparc".

The TestSharedForward executable and TestDynload module do not actually
link to a KWSys library, but it is nice to build them after the
libraries just like all other test binaries.

This also works around a universal binary bug in Xcode 2.x.  It forgets
to create the output directory for the executable before linking it.  We
avoid the problem by putting the library in the directory first.

Add fallback for detecting CPU speed from Windows registry on builds where USE_ASM_INSTRUCTIONS gets defined to 0. (Win64 builds.) Clean up methods to return false when not implemented or when they fail to detect the things they're supposed to detect. This file still needs a lot more work to have a fully working implementation on Win64 builds. Committing it now because it's slightly better than it was, and there is a need for the CPU speed detection code in projects that depend on kwsys. Will file a bug shortly to request that the missing implementations get filled in...

KWSys should not set variables outside its namespace.  It can honor the
EXECUTABLE_OUTPUT_PATH set by a host project, but tere is no need for it
to set a default in the host project cache.

In order to kill process trees we need to list all processes to find
those whose parent we are killing.  We implement process listing on
OpenSolaris by using "ps -ef" and parsing the resulting format:

     UID   PID  PPID   C    STIME TTY         TIME CMD
     %*s    %d    %d   %*[^\n]\n