[Kernel] make sure kernel build fail on all errors and address git am…

… error (#52)

* [Kernel] fail kernel build on all errors
* [Kernel] Check in all lose changes after add them all
Otherwise, the following git am will fail.

Makefile

@@ -33,6 +33,7 @@ $(addprefix $(DEST)/, $(MAIN_TARGET)): $(DEST)/% :
 	pushd $(BUILD_DIR)
 	git init
 	git add -f *
+	git commit -m "check in all loose files and diffs"
 
 	# patch debian changelog and update kernel package version
 	# git am ../patch/changelog.patch