'Returns true iff the gcc version pversion and cversion
are ABI compatible.'

@memoized
def _gcc_compiler_compare(self, pversion, cversion):

    plib = self._gcc_get_libstdcxx_version(pversion)
    clib = self._gcc_get_libstdcxx_version(cversion)
    if ((not plib) or (not clib)):
        return False
    return (plib == clib)
