Windows: Search '/' prefix only when cross compiling (#10994)

Commit dac78148 (...makes the mingw cross compiler work out of the
box..., 2007-08-02) added to CMAKE_SYSTEM_PROGRAM_PATH and
CMAKE_SYSTEM_LIBRARY_PATH paths like "/bin" and "/lib" with no Windows
drive letter so that cross-compiling to Windows from Linux would search
these paths under CMAKE_FIND_ROOT_PATH.  Later commit 2a782880 (...use
CMAKE_SYSTEM_PREFIX_PATH when possible, 2008-01-16) generalized this
approach by instead adding "/" to CMAKE_SYSTEM_PREFIX_PATH.

Both commits assumed that the paths would never match anything on
Windows hosts without a drive letter.  However, Windows evaluates these
paths relative to the current working drive letter so find_* commands
may report paths like "/lib/..." when paths like "c:/lib/..." exist on
what happens to be current drive.  Such drive-less paths are not
reliable when the working drive changes, so we should not use them.

Fix WindowsPaths.cmake to add '/' to CMAKE_SYSTEM_PREFIX_PATH only when
cross-compiling to Windows from a non-Windows host.  This will avoid
searching and finding local paths without a drive letter on Windows.

0 files changed, 0 insertions, 0 deletions