Revert "Makefile: replace $(RM) with rm"

This reverts commit bb0a33f030.

Makefile

@@ -111,7 +111,7 @@ export: www
 
 $(DATESTAMP):
 	mkdir -p build
-	rm $(wildcard build/.stamp-*)
+	$(RM) $(wildcard build/.stamp-*)
 	touch $@
 
 ### Regeln für den XSLT-Prozess ###
@@ -293,7 +293,7 @@ build/%.html.xhtml5-validate: build/%.html
 
 ### Die neuesten Chaosupdates holen ###
 $(WWW_CCC_DE_UPDATES).orig: $(DATESTAMP)
-	rm $@
+	$(RM) $@
 	$(WGET) -O $@ -4 http://www.ccc.de/de/rss/updates.rdf
 
 $(WWW_CCC_DE_UPDATES): $(WWW_CCC_DE_UPDATES).orig
@@ -302,5 +302,5 @@ $(WWW_CCC_DE_UPDATES): $(WWW_CCC_DE_UPDATES).orig
 ### Mr. Propper ###
 .PHONY: clean
 clean:
-	rm $(CLEAN) news.xml
-	rm -r portal
+	$(RM) $(CLEAN) news.xml
+	$(RM) -r portal