Makefile: release target

`make release` builds whackanop for different target OS/arch's, packages
them up and places the resulting archives in a release folder.

.gitignore

@@ -1,2 +1,4 @@
 *~
 c.out
+build
+release

Makefile

@@ -1,9 +1,14 @@
+VERSION := $(shell cat VERSION)
 SHELL := /bin/bash
-PKG = github.com/Clever/whackanop
-SUBPKGS =
-PKGS = $(PKG) $(SUBPKGS)
-
-.PHONY: test $(PKGS)
+PKG := github.com/Clever/whackanop
+SUBPKGS :=
+PKGS := $(PKG) $(SUBPKGS)
+EXECUTABLE := whackanop
+BUILDS := \
+	build/$(EXECUTABLE)-v$(VERSION)-darwin-amd64 \
+	build/$(EXECUTABLE)-v$(VERSION)-linux-amd64
+COMPRESSED_BUILDS := $(BUILDS:%=%.tar.gz)
+RELEASE_ARTIFACTS := $(COMPRESSED_BUILDS:build/%=release/%)
 
 test: $(PKG)
 
@@ -15,3 +20,22 @@ $(PKG):
 ifeq ($(HTMLCOV),1)
 	go tool cover -html=$(GOPATH)/src/$@/c.out
 endif
+
+build/$(EXECUTABLE)-v$(VERSION)-darwin-amd64:
+	GOARCH=amd64 GOOS=darwin go build -o "$@/$(EXECUTABLE)"
+build/$(EXECUTABLE)-v$(VERSION)-linux-amd64:
+	GOARCH=amd64 GOOS=linux go build -o "$@/$(EXECUTABLE)"
+
+%.tar.gz: %
+	tar -C `dirname $<` -zcvf "$<.tar.gz" `basename $<`
+
+$(RELEASE_ARTIFACTS): release/% : build/%
+	mkdir -p release
+	cp $< $@
+
+release: $(RELEASE_ARTIFACTS)
+
+clean:
+	rm -rf build release
+
+.PHONY: test $(PKGS) clean github-release

VERSION

@@ -0,0 +1 @@
+0.1.0