add release script (#163)

* add release script

* use more portable openssl

* add buildid= to ldflags

.gitignore

@@ -1,5 +1,6 @@
 cmd/dcrinstall/dcrinstall
 *.sw?
 .vscode
+release/
 vendor/
 *~

release.sh

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+# Copyright (c) 2019 The Decred developers
+# Use of this source code is governed by the ISC
+# license.
+
+set -ex
+
+TAG=$1
+REL=(-ldflags "-buildid= -X main.appBuild=release")
+
+PWD=$(pwd)
+PACKAGE=dcrinstall
+MAINDIR=$PWD/release/$PACKAGE-$TAG
+mkdir -p $MAINDIR
+
+SYS="darwin-amd64 freebsd-amd64 linux-386 linux-amd64 linux-arm64 openbsd-amd64 windows-386 windows-amd64"
+
+for i in $SYS; do
+    OS=$(echo $i | cut -f1 -d-)
+    ARCH=$(echo $i | cut -f2 -d-)
+    OUT="$MAINDIR/dcrinstall-$i-$TAG"
+    if [[ $OS = "windows" ]]; then
+	    OUT="$OUT.exe"
+    fi
+    echo "Building:" $OS $ARCH
+    env CGO_ENABLED=0 GOOS=$OS GOARCH=$ARCH go build -trimpath -tags 'safe,netgo' -o $OUT "${REL[@]}" ./cmd/dcrinstall
+done
+
+(cd $MAINDIR && openssl sha256 -r * > dcrinstall-$TAG-manifest.txt)