Customer reported problems detecting the Cray compiler on their Apollo80 system. We were checking for the __CRAYXC and __CRAYXE predefined macros. These macros reflect the platform that the compiler is running on, i.e. Cray XC and Cray XE machines. Naturally, this didn't work on Apollo80.
This commit uses the official Cray compiler identification macros which are defined on every platform:
CCE Version C Macro C++ Macro Fortran Macro
============ ======== ========= =============
version < 9 _CRAYC _CRAYC _CRAYFTN
version >= 9 __cray__ __cray__ _CRAYFTN