dist.sh: use go build option to strip binaries

30% release binary size reduction

dist.sh

@@ -25,7 +25,8 @@ for os in windows linux darwin; do
     fi
     BUILD=$(mktemp -d ${TMPDIR:-/tmp}/oauth2_proxy.XXXXXX)
     TARGET="oauth2_proxy-$version.$os-$arch.$goversion"
-    GOOS=$os GOARCH=$arch CGO_ENABLED=0 go build -o $BUILD/$TARGET/oauth2_proxy$EXT || exit 1
+    GOOS=$os GOARCH=$arch CGO_ENABLED=0 \
+        go build -ldflags="-s -w" -o $BUILD/$TARGET/oauth2_proxy$EXT || exit 1
     pushd $BUILD
     tar czvf $TARGET.tar.gz $TARGET
     mv $TARGET.tar.gz $DIR/dist