When building gstreamer, gtkdoc-mkdb is called in doc/gst/. For me it emits
numerous WARNINGs and even ERRORs regarding malformed comment blocks. However,
that doesn't change the fact that the documentation still *would* build and
would look fine, *if* there weren't a silent failure.

Line 209 of doc/gst/Makefile.am: @if grep "WARNING:" sgml-build.log > /dev/null;
then exit 1; fi

Obviously the docs should be perfect, but imperfection shouldn't make the build
fail -- especially when gtkdoc-mkdb returns an exit code of 0. Not to mention,
it's hypocritical that it would fail on WARNINGs but succeed on ERRORs. I
suggest removing the line entirely, so that gstreamer will actually build for me :).