gnattools: Clean config.cache (PR70173)

The config.cache file should be deleted by "make distclean", just like
config.log and config.status .  The directory itself is still not deleted
(just like the gotools and libcc1 directories).


gnattools/
	PR bootstrap/70173
	* Makefile.in (distclean): Also delete config.cache .

From-SVN: r234721

gnattools/ChangeLog

+2016-04-04  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR bootstrap/70173
+	* Makefile.in (distclean): Also delete config.cache .
+
 2015-12-06  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR ada/50048

gnattools/Makefile.in

@@ -309,7 +309,7 @@ mostlyclean:
 clean:
 
 distclean:
-	$(RM) Makefile config.status config.log
+	$(RM) Makefile config.status config.log config.cache
 
 maintainer-clean: