add prereq checks for the documentation (#1400)

SVN-Revision: 6365

docs/Makefile

@@ -1,5 +1,12 @@
+ifeq ($(TOPDIR),)
+  TOPDIR:=${CURDIR}/..
+endif
+
+include $(TOPDIR)/rules.mk
+include $(INCLUDE_DIR)/prereq.mk
+
 MAIN = openwrt.tex
-DEPS = $(MAIN) Makefile config.tex network.tex network-scripts.tex network-scripts.tex wireless.tex build.tex adding.tex bugs.tex
+DEPS = $(MAIN) Makefile config.tex network.tex network-scripts.tex network-scripts.tex wireless.tex build.tex adding.tex bugs.tex .prereq
 
 all:
 	$(MAKE) cleanup
@@ -7,6 +14,10 @@ all:
 	$(MAKE) openwrt.pdf openwrt.html
 	$(MAKE) cleanup
 
+.prereq:
+	$(MAKE) prereq
+	touch $@
+
 openwrt.html: $(DEPS)
 	htlatex $(MAIN)
 
@@ -19,6 +30,12 @@ clean: cleanup
 cleanup: FORCE
 	rm -f *.log *.aux *.toc *.out *.lg *.dvi *.idv *.4ct *.4tc *.xref *.tmp *.dvi
 
+$(eval $(call RequireCommand,pdflatex, \
+	You need to install LaTeX to build the OpenWrt documentation \
+))
+$(eval $(call RequireCommand,htlatex, \
+	You need to install tex4ht to build the OpenWrt documentation \
+))
 
 FORCE:
 .PHONY: FORCE