ref(Makefile): compress with upx directly

The `goupx` tool isn't needed since go 1.6.

Author: mboersma

Makefile

@@ -16,7 +16,7 @@ DEV_ENV_CMD := ${DEV_ENV_PREFIX} ${DEV_ENV_IMAGE}
 # doesn't allow +, so we use -.
 BINARY_DEST_DIR := rootfs/usr/bin
 # Common flags passed into Go's linker.
-LDFLAGS := "-s -X main.version=${VERSION}"
+LDFLAGS := "-s -w -X main.version=${VERSION}"
 # Docker Root FS
 BINDIR := ./rootfs
 
@@ -35,9 +35,9 @@ glideup:
 # the Docker environment. Other alternatives are cross-compiling, doing
 # the build as a `docker build`.
 build:
-	${DEV_ENV_PREFIX} -e CGO_ENABLED=0 ${DEV_ENV_IMAGE} go build -a -installsuffix cgo -ldflags ${LDFLAGS} -o ${BINARY_DEST_DIR}/boot boot.go || exit 1
+	${DEV_ENV_PREFIX} -e CGO_ENABLED=0 ${DEV_ENV_IMAGE} go build -a -installsuffix cgo -ldflags ${LDFLAGS} -o ${BINARY_DEST_DIR}/boot boot.go
 	@$(call check-static-binary,$(BINARY_DEST_DIR)/boot)
-	${DEV_ENV_PREFIX} ${DEV_ENV_IMAGE} goupx ${BINARY_DEST_DIR}/boot || exit 1
+	${DEV_ENV_PREFIX} ${DEV_ENV_IMAGE} upx -9 ${BINARY_DEST_DIR}/boot
 
 test:
 	${DEV_ENV_CMD} sh -c 'go test $$(glide nv)'