Provides a macro to check if a header file can be included in CXX.
CHECK_INCLUDE_FILE_CXX(<include> <variable> [<flags>])
Check if the given <include> file may be included in a CXX source file and store the result in an internal cache entry named <variable>. The optional third argument may be used to add compilation flags to the check (or use CMAKE_REQUIRED_FLAGS below).
The following variables may be set before calling this macro to modify the way the check is run:
See modules CheckIncludeFile and CheckIncludeFiles to check for one or more C headers.