Include the doc dir in DIST_SUBDIRS instead of EXTRA_DIST

And explicitly specify what we want included in EXTRA_DIST of doc/Makefile.am,
otherwise make dist picks up whatever random junk you might have laying around
in that dir at the time you run it.

Tweak the top level delegation targets, because this means distclean will be
run in the doc dir by default now without our help.

Makefile.am

@@ -2,6 +2,8 @@ AUTOMAKE_OPTIONS = subdir-objects
 
 lib_LTLIBRARIES = libopus.la
 
+DIST_SUBDIRS = doc
+
 INCLUDES = -I$(top_srcdir)/include -I$(top_srcdir)/celt -I$(top_srcdir)/silk -I$(top_srcdir)/silk/float -I$(top_srcdir)/silk/fixed
 
 include celt_sources.mk
@@ -79,7 +81,7 @@ opus_custom_demo_SOURCES = celt/opus_custom_demo.c
 opus_custom_demo_LDADD = libopus.la -lm
 endif
 
-EXTRA_DIST = opus.pc.in opus-uninstalled.pc.in doc
+EXTRA_DIST = opus.pc.in opus-uninstalled.pc.in
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = opus.pc
@@ -109,10 +111,7 @@ install-data-local:
 	@[ -n "$(NO_DOXYGEN)" ] || $(MAKE) $(AM_MAKEFLAGS) -C doc install
 
 clean-local:
-	$(MAKE) $(AM_MAKEFLAGS) -C doc clean
-
-distclean-local:
-	$(MAKE) $(AM_MAKEFLAGS) -C doc distclean
+	-$(MAKE) $(AM_MAKEFLAGS) -C doc clean
 
 uninstall-local:
 	$(MAKE) $(AM_MAKEFLAGS) -C doc uninstall

doc/Makefile.am

@@ -9,7 +9,7 @@ DOCINPUTS = $(top_srcdir)/include/opus.h \
             $(top_srcdir)/doc/footer.html \
             $(top_srcdir)/doc/customdoxygen.css
 
-EXTRA_DIST = Doxyfile.in opus_logo.svg
+EXTRA_DIST = customdoxygen.css Doxyfile.in footer.html header.html opus_logo.svg
 
 
 if HAVE_DOXYGEN