Add Golang issue link re: -trimpath to Makefile
Per the request in add a link to the issue in case this situation
changes in the future.
@@ -67,6 +67,7 @@ GOPATHS=$(shell echo ${GOPATH} | tr ":" "\n" | tr ";" "\n")
TESTFLAGS_RACE=
GO_BUILD_FLAGS=
+# See Golang issue re: '-trimpath': https://github.com/golang/go/issues/13809
GO_GCFLAGS=$(shell \
set -- ${GOPATHS}; \
echo "-gcflags=-trimpath=$${1}/src"; \
