bug#5934: 24.0.50; get rid of "unix" pre-defined macro when preprocessing Makefile

[Chong Yidong]

Miles Bader <miles.bader.fz@renesas.com> writes:

> Emacs uses the C preprocessor to process src/Makefile.in, and the CPP on
> many systems defines the token "unix" (to be "1") for historical
> reasons.
>
> This has bad results if some of the Makefile contents include that
> token; in particular, on my system, the definition of ALL_CFLAGS
> contains " -I/usr/include/gio-unix-2.0/", and due to the bogus
> predefined unix macro, this ends up as something that's not even legal
> compiler command-line syntax.
>
> Luckily,  the "unix" macro isn't actually used by Makefile
> preprocessing, so it's simple enough to add that to the list of things
> which the Emacs configure script explicitly undefines when doing
> Makefile preprocessing.
>
> The following patch does this:

Looks good, could you check it into the trunk?