Merge pull request #6470 from kaspar030/fix_maindir_clean_target

make: remove pkg/*/ from clean targets

Makefile

@@ -20,11 +20,11 @@ docclean:
 
 clean:
 	@echo "Cleaning all build products for the current board"
-	@find ./pkg/ ./examples/ ./tests/ -maxdepth 2 -mindepth 2 -type f -name Makefile -execdir "${MAKE}" clean ';'
+	@find ./examples/ ./tests/ -maxdepth 2 -mindepth 2 -type f -name Makefile -execdir "${MAKE}" clean ';'
 
 distclean: docclean
 	@echo "Cleaning all build products"
-	@find ./pkg/ ./examples/ ./tests/ -maxdepth 2 -mindepth 2 -type f -name Makefile -execdir "${MAKE}" distclean ';'
+	@find ./examples/ ./tests/ -maxdepth 2 -mindepth 2 -type f -name Makefile -execdir "${MAKE}" distclean ';'
 
 welcome:
 	@echo "Welcome to RIOT - The friendly OS for IoT!"