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 <firstname.lastname@example.org>