[config] Make gperf/antlr maintainer tools, support distcheck

Updated configure to allow gperf/antlr to be missing if products are
in distribution (allows option of building w/o those tools)
Removed circular dependency of antlr products on clean
Added missing ffmpeg-compat.h header (correct dist)
Include gperf/antlr products in dist
gperf/antlr products removed with maintainer-clean
Support vpath builds, distcheck passes
Added support for non-verbose builds

Makefile.am

@@ -2,10 +2,22 @@ ACLOCAL_AMFLAGS = -I m4
 
 sysconf_DATA = forked-daapd.conf
 
-EXTRA_DIST = configure
 SUBDIRS = sqlext src
 
-man_MANS = forked-daapd.8
+dist_man_MANS = forked-daapd.8
+
+nobase_dist_doc_DATA = \
+	UPGRADING \
+	README.md \
+	README_PULSE.md \
+	README_SMARTPL.md \
+	scripts/antlr35_install.sh \
+	scripts/freebsd_install_10.1.sh \
+	scripts/freebsd_start_10.1.sh \
+	scripts/pairinghelper.sh
+
+EXTRA_DIST = \
+	forked-daapd.conf
 
 install-data-hook:
 	$(MKDIR_P) "$(DESTDIR)$(localstatedir)/cache/$(PACKAGE)/libspotify"