makefile: update according to ipfs/go-ipfs-example-plugin#9

Makefile

@@ -4,16 +4,22 @@ GO111MODULE = on
 GOCC ?= go
 GOFLAGS ?=
 
-# make reproducable
-GOFLAGS += -asmflags=all=-trimpath="$(GOPATH)" -gcflags=all=-trimpath="$(GOPATH)"
-
 # If set, override the install location for plugins
 IPFS_PATH ?= $(HOME)/.ipfs
 
 # If set, override the IPFS version to build against. This _modifies_ the local
 # go.mod/go.sum files and permanently sets this version.
 IPFS_VERSION ?= $(lastword $(shell $(GOCC) list -m github.com/ipfs/go-ipfs))
 
+# make reproducible
+ifneq ($(findstring /,$(IPFS_VERSION)),)
+# Locally built go-ipfs
+GOFLAGS += -asmflags=all=-trimpath="$(GOPATH)" -gcflags=all=-trimpath="$(GOPATH)"
+else
+# Remote version of go-ipfs (e.g. via `go get -trimpath` or official distribution)
+GOFLAGS += -trimpath
+endif
+
 .PHONY: install build
 
 go.mod: FORCE