Fix the %build section of the spec file to pass in proper CFLAGS
    
    The wrong assumptions were being made about what generate/unix/Makefile.config
    would do with passed in values of OPT_CFLAGS, causing CWARNINGFLAGS to be
    ignore in that makefile.  For packaging purposes, OPT_CFLAGS needs to be
    used to pass in distro required values; we needed to add to that all of the
    CWARNINGFLAGS so that we do not have to rewrite or significantly patch large
    portions of the original makefile.
    
    Signed-off-by: Al Stone <ahs3@redhat.com>