This adds the configured KWSys header files to the library targets that
implement their APIs so that they show up in IDE project files.

On Windows the GetLongPathName API function does not work on some
filesystems even if the file exists.  In this case we should just use
the original long path name and not the GetShortPathName result.
See issue #8480.

This patch from Philip Lowman teaches SystemTools::GetRealPath to deal
with paths that do not exist by dealing with the case that realpath
returns NULL.  See issue #8423.

The test is supposed to terminate quickly when its child crashes, but
that seems to take over 10s on busy systems.  This extends the test's
timeout to 30s to help it pass when running on a busy system.

On Windows the KWSys System package generates escapes for command-line
arguments.  This fix enables quoting of the empty string as an argument.
This also adds a test to pass an empty argument to a custom command.

BUG: Do not copy permissions of files when making the copy in an install rule. If the source file was read-only, this prevents the subsequent set of the destination file's modification time, making the copied file always different in time-stamp than the original and always installing a new file with a new time stamp (but the same content) causing unnecessary downstream incremental rebuilds. As part of this fix, add an optional copyPermissions parameter to the SystemTools routines CopyFileIfDifferent, CopyFileAlways, CopyAFile and CopyADirectory. The copyPermissions parameter defaults to true to preserve the behavior of these routines for existing callers.

The SystemInformation component of KWSys requires Process and
FundamentalType.

KWSys component dependencies must be enforced before any tests for
enabled components are done.  This moves the dependency enforcement code
to be as early as possible.

See issue #7797.

In SharedForward, the call to execvp warned on MinGW because the
signature declared in process.h has an extra const.  We use an explicit
cast to convert the pointer type.

This tests the basic capability of running another executable from the
build tree.

The windows execvp function does not re-escape arguments correctly.
Instead we generate the escape sequences before calling it.

To detect when the launcher is running from the build tree we now test
if the directory containing it is the same as the build-tree directory
using an inode test instead of string comparison.  This makes it more
robust on case-insensitive filesystems and other quirky situations.

In SharedForward we are only dealing with command-line-length strings so we
need not worry about integer overflow.

ENH: Improve FILE GLOB_RECURSE handling of symlinks with a new CMake policy. CMP0009 establishes NEW default behavior of not recursing through symlinks. OLD default behavior or explicit FOLLOW_SYMLINKS argument to FILE GLOB_RECURSE will still recurse through symlinks.

ENH: Add RecurseThroughSymlinks data member to kwsys::Glob. Allows recursive globs to skip symlinks when necessary. Default to true for backwards compatible behavior. Used from the ctest coverage handler to avoid recursing through the '/Applications' directory on the Mac looking for *.da files... Should fix the hangs reported recently by Mac CMake dashboard submitters.

According to "man select" on Linux it is possible that select() lies
about data being ready on a pipe in some subtle cases.  We deal with
this by switching to non-blocking i/o and checking for EAGAIN.  See
issue #7180.

  - Patch from Matthew McCormick, slightly tweaked
  - See issue #6833

BUG:  FormatMessage can return a NULL message.  Add check for NULL pointer.

BUG:cpuinfo format are different between Linux and Cygwin. Cygwin does not have physical id tag or cpu cores tag.

ENH: avoid divide by zero, temporary fix until cygwin cpu file is read better, bad cpu info is better than a crash

BUG:Fixed NumberOfLogicalCPU, NumberOfPhysicalCPU and LogicalProcessorsPerPhysical under Linux. Some part was just wrong. Some other part missed to take the multicore value into account.

  - Add an argument to registry read/write/delete methods to specify
    a 32-bit or 64-bit view.
  - Default is the bit-ness of the running program.
  - See issue #7095.