Revert part of "Makefile: add support for DESTDIR"

This removes my editing on the patch received by Chris Pickel, as I didn't
understand the purpose of DESTDIR.

Noticed-by: Chris Pickel <sfiera@macports.org>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Makefile

@@ -56,9 +56,9 @@ install: all
 	rm -rf $(DESTDIR)$(CACHE_ROOT)/*
 
 uninstall:
-	rm -f $(DESTDIR)$(CGIT_SCRIPT_PATH)/$(CGIT_SCRIPT_NAME)
+	rm -f $(CGIT_SCRIPT_PATH)/$(CGIT_SCRIPT_NAME)
-	rm -f $(DESTDIR)$(CGIT_SCRIPT_PATH)/cgit.css
+	rm -f $(CGIT_SCRIPT_PATH)/cgit.css
-	rm -rf $(DESTDIR)$(CACHE_ROOT)
+	rm -rf $(CACHE_ROOT)
 
 clean:
 	rm -f cgit VERSION *.o