If you add a platform check for a specific OS or want to
modify compiler flags, rather then introducing
IF(CMAKE_SYSTEM_NAME MATCHES...) in
configure.cmake, add them to the
apropriate section in
cmake/os/.
For example, Solaris-specific adjustments are made in
my_platform.cmakecmake/os/SunOS.cmake. This file is
included when you compile on Solaris.