Eliminate bogus re-build when no images exist ("make ..." re-builds

 the current directory if "..." is empty).



git-svn-id: https://svn.osgeo.org/grass/grass/trunk@40147 15284696-431f-4ddb-bdfa-cd5b030d7da7

include/Make/Html.make

@@ -13,7 +13,9 @@ IMGSRC := $(wildcard *.png) $(wildcard *.jpg)
 
 $(HTMLDIR)/%.html: %.html %.tmp.html $(HTMLSRC) | $(HTMLDIR)
 	$(PYTHON) $(GISBASE)/tools/mkhtml.py $* > $@
+ifneq ($(strip $(IMGSRC)),)
 	$(MAKE) $(patsubst %,$(HTMLDIR)/%,$(IMGSRC))
+endif
 
 $(HTMLDIR)/%.png: %.png | $(HTMLDIR)
 	$(INSTALL_DATA) $< $@