[PATCH 3/4] doc: use stamp file for html docs

[David Bremner]

These are less time consuming than the texi docs to rebuild (because
the texi rebuild triggers info rebuild), but still take noticable time.
---
 doc/Makefile.local | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/doc/Makefile.local b/doc/Makefile.local
index 2a701646..a8fee537 100644
--- a/doc/Makefile.local
+++ b/doc/Makefile.local
@@ -50,10 +50,13 @@ sphinx-html: | $(DOCBUILDDIR)/.roff.stamp
 sphinx-texinfo: | sphinx-html
 sphinx-info: | sphinx-texinfo
 
-sphinx-html:
+sphinx-html: $(DOCBUILDDIR)/.html.stamp
+
+$(DOCBUILDDIR)/.html.stamp: $(ALL_RST_FILES)
 	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(DOCBUILDDIR)/html
+	touch $@
 
-sphinx-texinfo: .texi.stamp
+sphinx-texinfo: $(DOCBUILDDIR)/.texi.stamp
 
 $(DOCBUILDDIR)/.texi.stamp: $(ALL_RST_FILES)
 	$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(DOCBUILDDIR)/texinfo
@@ -142,4 +145,5 @@ $(dir)/config.dox: version.stamp
 	echo "INPUT=${srcdir}/lib/notmuch.h" >> $@
 
 CLEAN := $(CLEAN) $(DOCBUILDDIR) $(DOCBUILDDIR)/.roff.stamp $(DOCBUILDDIR)/.texi.stamp
+CLEAN := $(CLEAN) $(DOCBUILDDIR)/.html.stamp
 CLEAN := $(CLEAN) $(MAN_GZIP_FILES) $(MAN_ROFF_FILES) $(dir)/conf.pyc $(dir)/config.dox
-- 
2.20.1