Introduce macros for language specific compiler options
    
    Introduce new language specific __global_fooflags for C, C++ and Fortran
    This looks mildly strange and suspicious since because the global flags
    get pulled in indirectly via %optflags (that doesn't change here but becomes
    more obvious).
    
    Depends on previous commit (8fe5b078719c7f29c7bf7a681c7ec8445f5f7817)
    which was done separately to make the actual change (or lack of thereof)
    stand out here.
    
    This is not supposed to change any actual values for current usages,
    so if it does it's a bug.
    
    However there's a minor bonus involved for Fortran users who can now get
    the correct FFLAGS/FCFLAGS for non-autoconf projects too by using
    __global_fflags/fcflags