Do not include m4 files in dist

Makefile.am

@@ -2,10 +2,7 @@
 
 SUBDIRS = src conf doc web admin win32 examples tests
 
-EXTRA_DIST = README.md HACKING m4/acx_pthread.m4 m4/ogg.m4 \
-    m4/theora.m4 m4/vorbis.m4 m4/speex.m4 \
-    m4/xiph_compiler.m4 m4/xiph_curl.m4 m4/xiph_net.m4 \
-    m4/xiph_types.m4 m4/xiph_xml2.m4
+EXTRA_DIST = README.md HACKING
 
 docdir = $(datadir)/doc/$(PACKAGE)
 doc_DATA = README.md AUTHORS COPYING NEWS ChangeLog