Merge pull request #68 from guyush1/make-clean-posix-compliance

Made `make clean` POSIX compliant

Author: guyush1

Makefile

@@ -86,7 +86,7 @@ _pack-%: build-%-$(BUILD_TYPE)
 	fi
 
 clean-git-packages:
-	git submodule foreach '[[ "$$sm_path" == src/submodule_packages/* ]] && git clean -xffd && git restore .'
+	git submodule foreach 'echo "$$sm_path" | grep "^src/submodule_packages/.*" && git clean -xffd && git restore .'
 
 clean: clean-git-packages
 	rm -rf build