This removes SystemTools::FileExistsInParentDirectories from KWSys since
it is a special-purpose method that is not generally useful.

When SystemTools::GetParentDirectory was fixed to never remove the root
path component from a full path we violated an assumption made by
IsSubDirectory that eventually GetParentDirectory returns an empty
string.  This led to an infinite loop if the potential parent directory
is empty, so we explicitly avoid that case.

The previous change to this method broke cases where the input path does
not exist.  The SystemTools::GetParentDirectory method is redundant with
the more robust SystemTools::GetFilenamePath.  This replaces its
implementation to just call GetFilenamePath.

BUG: SystemTools::GetParentDirectory() will crash if "/" is passed in as argement. Valid check is added to make sure the input argment exists, and if "/" is passed in, empty string will be returned.

All KWSys C symbol names begin with the KWSYS_NAMESPACE defined at
configuration time.  For ease of editing we write canonical names with
the prefix 'kwsys' and use macros to map them to the configured prefix
at preprocessing time.  In the case of standalone KWSys, the prefix is
'kwsys', so the macros were previously defined to their own names.

We now skip defining the macros in the identity case so that the final
symbol names are never themselves macros.  This will allow the symbols
to be further transformed behind the scenes to help linkers in special
cases on some platforms.

Previously KWSys SystemInformation parsed this file assuming a strict
order and set of fields, but the order is not reliable.  This
generalizes the implementation to support any order and extra fields.

BUG: comment out faulty seekp which make kwsys::*stringstream fails on platform with no std::*stringstream implementation

STYLE:Empty commit just add information about rev 1.15: the reason is that long is 64-bit on gcc on Linux because it uses the LP64 data model whereas long is 32-bit on VS 64-bit because it uses the LLP64 model (ref: http://en.wikipedia.org/wiki/64-bit#64-bit_data_models )

COMP:Fix warning on VS 64bit. Don't why gcc 4.3.2 didn't catch this one on a 64bit machine with -Wconversion on.

COMP:Fixed gcc 4.3.2 warning with -O1 and above: ignoring return value of read'), declared with attribute warn_unused_result

This provides an API for parent projects to use to specify values to be
set in the LABELS properties of KWSys libraries, executables, and tests.

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.