configure.ac: add -Werror to default compiler options

[Dan Kegel]

On Wed, Aug 31, 2011 at 11:13 PM, Octavian Voicu
<octavian.voicu at gmail.com> wrote:
> On Thu, Sep 1, 2011 at 4:27 AM, Dan Kegel <dank at kegel.com> wrote:
>> At which point it would probably be a fine idea to add -Werror by default;
>> buildbot will help keep everyone in sync, even if they're using a compiler
>> that doesn't catch as many warnings as the one buildbot uses.
>
> Have you tried compiling on 64-bit? There are still a handful of
> compile warnings there (most in oleaut32/tmarshal.c; then
> setupapi/devinst.c; dsound+winmm).

OK, finally tried this myself.  It looks like oleaut32/tmarshal.c
is the only serious obstacle left.
- Dan