CheckIPOSupported: New module to check for compiler/cmake IPO support

Help/manual/cmake-modules.7.rst

Help/module/CheckIPOSupported.rst

Help/release/dev/CheckIPOSupported.rst

Modules/CheckIPOSupported.cmake

Modules/CheckIPOSupported/CMakeLists-C.txt.in

Modules/CheckIPOSupported/CMakeLists-CXX.txt.in

Modules/CheckIPOSupported/foo.c

Modules/CheckIPOSupported/foo.cpp

Modules/CheckIPOSupported/main.c

Modules/CheckIPOSupported/main.cpp

Modules/Platform/Linux-Intel.cmake