Add top-level Makefile and RPM spec file for packaging

Top-level Makefile can create tar and RPM files to release.
Also add *.tar.gz to .gitignore.

Makefile

@@ -0,0 +1,34 @@
+NAME := alsa-scarlett-gui
+VERSION := $(shell git describe --abbrev=4 --always --tags | sed 's/-/./g')
+NAMEVER := $(NAME)-$(VERSION)
+TAR_FILE := $(NAMEVER).tar
+TARGZ_FILE := $(TAR_FILE).gz
+SPEC_FILE := $(NAME).spec
+
+default:
+	@echo "alsa-scarlett-gui"
+	@echo
+	@echo "If you want to build and install from source, please try:"
+	@echo "  cd src"
+	@echo "  make -j4"
+	@echo "  sudo make install"
+	@echo
+	@echo "This Makefile knows about packaging:"
+	@echo "  make tar"
+	@echo "  make rpm"
+
+tar: $(TARGZ_FILE)
+
+$(TARGZ_FILE):
+	git archive --format=tar --prefix=$(NAMEVER)/ HEAD > $(TAR_FILE)
+	sed 's_VERSION$$_$(VERSION)_' < $(SPEC_FILE).template > $(SPEC_FILE)
+	tar --append -f $(TAR_FILE) \
+		--transform s_^_$(NAMEVER)/_ \
+		--owner=root --group=root \
+		$(SPEC_FILE)
+	rm -f $(SPEC_FILE)
+	gzip < $(TAR_FILE) > $(TARGZ_FILE)
+	rm -f $(TAR_FILE)
+
+rpm: $(TARGZ_FILE)
+	rpmbuild -tb $(TARGZ_FILE)