add cross compile script

.gitignore

@@ -0,0 +1 @@
+/bin

build.sh

@@ -0,0 +1,16 @@
+#!/bin/sh
+APP="git-hours"
+# OS별로 빌드함.
+GOOS=linux GOARCH=amd64 go build -o ./bin/linux/${APP} git-hours.go
+GOOS=windows GOARCH=amd64 go build -o ./bin/windows/${APP}.exe git-hours.go
+GOOS=darwin GOARCH=amd64 go build -o ./bin/darwin/${APP} git-hours.go
+
+# Github Release에 업로드 하기위해 압축
+cd ./bin/linux/ && tar -zcvf ../${APP}_linux.tgz . && cd -
+cd ./bin/windows/ && tar -zcvf ../${APP}_windows.tgz . && cd -
+cd ./bin/darwin/ && tar -zcvf ../${APP}_darwin.tgz . && cd -
+
+# 삭제
+rm -rf ./bin/linux
+rm -rf ./bin/windows
+rm -rf ./bin/darwin