AC_GNU_SOURE (was Re: [cairo] (no subject)

[Behdad Esfahbod]

> I dropped the AC_REVISION and AC_GNU_SOURCE calls since they didn't
> seem necessary, (or are at least irrelevant to what this patch was
> doing). Let me know if we actually need them for something.

Theoretically AC_GNU_SOURCE is not neede, but seems like
currently one of the xlib headers (IIRC) is definig XOPEN_SOURCE
macro in its public headers, which it shouldn't.  The result is
that glibc headers hide many features that are not supported by
XOPEN, including but not limited to sincos().  Adding
AC_GNU_SOURCE on the other hand, makes glibc expose whatever
features it has, which is not anyway and pretty harmless.  The
extreme is that we are shadowin some glibc extensions, at least
we would know.  So, I suggest we add it when the sincos patch is
applied.

--behdad
http://behdad.org/