Add a new SYSTEM_ONLY mode for CMAKE_FIND_ROOT_PATH.

This new SYSTEM_ONLY mode allows for the intrinsic system paths
used for find_* commands to get re-rooted from the CMAKE_FIND_ROOT_PATH
variable while maintaining original user-specified paths.  The intent is
for this to be the preferred mode for cross compiling.  It allows for a
a restricted default search within a desired system root but also
lets the user specify explicit search paths anythere on the host system.
CMake Nightly Date Stamp
CMake Nightly Date Stamp
StringUuid: Work around missing std::hex
Merge topic 'string-uuid' into next

210f6b7b StringUuid: Work around missing std::hex
StringUuid: Implement new string(UUID) sub-command.
Merge topic 'string-uuid' into next

180eb8f7 StringUuid: Implement new string(UUID) sub-command.
Merge topic 'add-find-root-system_only-mode' into next

2e08cf8e Add a new SYSTEM_ONLY mode for CMAKE_FIND_ROOT_PATH.
Merge topic 'wxWidgets-paths'

33286235 FindwxWidgets: Improve path detection logic when cross-compiling.
Merge topic 'wxWidgets-cflags'

e6fa6e60 UsewxWidgets: CFLAGS are expected to be a string here, not a list.
Merge branch 'master' into next
StringUuid: Try to work around mangling issues
Merge topic 'string-uuid' into next

c158564f StringUuid: Try to work around mangling issues
StringUuid: Implement new string(UUID) sub-command.
Merge topic 'string-uuid' into next

db8ce1fd StringUuid: Implement new string(UUID) sub-command.
MSVC: Define 'WIN32' for Windows Store and Windows Phone

This was accidentally left out of commit c72f0887 (MSVC: Add default
WindowsPhone and WindowsStore compile flags, 2014-07-28).
Load CMAKE_USER_MAKE_RULES_OVERRIDE[_ASM] for assembler (#15108)

This is already done for C, CXX, and Fortran.
Merge topic 'asm-user-override-files' into next

487f147f Load CMAKE_USER_MAKE_RULES_OVERRIDE[_ASM] for assembler (#15108)
Merge topic 'vs-windows-apps' into next

57849f33 MSVC: Define 'WIN32' for Windows Store and Windows Phone
StringUuid: Improve diagnostic messages and testing.