b=530038; add build warning if configure or config.status are out of date; r=ted

Makefile.in

@@ -88,7 +88,7 @@ DIST_GARBAGE = config.cache config.log config.status config-defs.h \
    netwerk/necko-config.h xpcom/xpcom-config.h xpcom/xpcom-private.h \
    $(topsrcdir)/.mozconfig.mk $(topsrcdir)/.mozconfig.out
 
-default alldep all::
+default alldep all:: $(topsrcdir)/configure config.status
 	$(RM) -rf $(DIST)/sdk
 	$(RM) -rf $(DIST)/include
 	$(RM) -rf $(DIST)/private
@@ -96,6 +96,20 @@ default alldep all::
 	$(RM) -rf $(DIST)/bin/components
 	$(RM) -rf _tests
 
+$(topsrcdir)/configure: $(topsrcdir)/configure.in
+	@echo "STOP!  configure.in has changed, and your configure is out of date."
+	@echo "Please rerun autoconf and re-configure your build directory."
+	@echo "To ignore this message, touch 'configure' in the source directory,"
+	@echo "but your build might not succeed."
+	@exit 1
+
+config.status: $(topsrcdir)/configure
+	@echo "STOP!  configure has changed and needs to be run in this build directory."
+	@echo "Please rerun configure."
+	@echo "To ignore this message, touch 'config.status' in the build directory,"
+	@echo "but your build might not succeed."
+	@exit 1
+
 # Build pseudo-external modules first when export is explicitly called
 export::
 	$(RM) -rf $(DIST)/sdk