Your patch: don't configure libobjc on Darwin

[Stan Shebs]

Nicola Pero wrote:

>
><fuming with rage after seeing one of our GNUstep users seriously (and
>rightfully so) angry>
>
>He might be using -fgnu-runtime.  So what ?  The whole purpose of
>-fgnu-runtime and -fnext-runtime is to change the compiler behaviour *at
>runtime* (as opposed to configure time) between the two runtimes!
>
>It seems to me that you have applied a radical patch causing a major
>regression (since the GNU Objective-C runtime was available on Darwin in
>all previous releases of GCC, and is no longer available now) just because
>you don't want to spend twenty minutes figuring out how to install both
>runtimes together on darwin and switch safely between the two.  I'm afraid
>you'll have to fix your laziness, or revert your damaging patch.
>
It's a bit more than a 20-minute job I'm afraid, because on Darwin
both the NeXT and GNU libraries and headers are mutually exclusive
and will try to override each other in bad ways.  I poked at this
very issue a couple years ago, and it took about 20 minutes :-) to
learn the full nastiness of the problem; for instance, dealing with
conflicting headers would probably require significant fixincludes
hacking, so that you don't get disasterized by seeing NeXT headers
when compiling with -fgnu-runtime.

Geoff's change is a reasonable bandaid, but it is possible to make
the two runtimes coexist peacefully, and would be much less work
than to merge them into a single runtime, so we should try for the
coexistence patch.  On the plus side, it will be easy to test; just
make the ObjC testsuite loop over -fgnu-runtime and -fnext-runtime.

Stan