Update documentation cleanfiles.
Add a new intermediate file generated when building the spec.
It's necessary to remove all intermediates to pass `make distcheck`.
@@ -91,6 +91,7 @@ CLEANFILES = $(SPEC_TEX:%.tex=%.aux) \
Vorbis_I_spec.lg Vorbis_I_spec.log \
Vorbis_I_spec.out Vorbis_I_spec.tmp \
Vorbis_I_spec.toc Vorbis_I_spec.xref \
+ Vorbis_I_spec.out.ps \
zzVorbis_I_spec.ps
DISTCLEANFILES = $(built_docs)
