Makefile: set GOPROXY only if it's missing
As GOPROXY is set by default by Go 1.13 already. Also, since Go before
1.13 supports only single value for GOPROXY, we cannot set it to 1.13+
default value.
@@ -11,7 +11,10 @@ endif
# Use the Go module mirror (https://blog.golang.org/module-mirror-launch).
# This speeds up build time and protects against disappearing dependencies.
+ifeq ($(shell (go env GOPROXY)),)
export GOPROXY=https://proxy.golang.org
+endif
+
LDFLAGS := "-X github.com/kinvolk/lokoctl/cli/cmd.version=$(VERSION) -extldflags '-static'"
