Cray: Fix Cray compiler detection on new platforms

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
21 jobs for cray-compiler-detection