Mostly from Eric Botcazou <botcazou@adacore.com>

        * rs6000-core.c: ANSIfy all function definitions.
        Add missing function prototypes.
        (ptr_to_uint): New type.
        (rs6000coff_core_p): Use it as intermediate step in casts.
        (rs6000coff_core_file_matches_executable_p): Likewise.
        * xcoff-target.h (rs6000coff_core_p): Fix prototype.
        (rs6000coff_core_file_matches_executable_p): Likewise.