Makefile+release: only use -trimpath on release script

Allows lnd to still be compiled with go1.12.x, tho users with go1.13 can
still verify release binaries.

Makefile

@@ -34,8 +34,8 @@ LINT_COMMIT := v1.18.0
 GOACC_COMMIT := ddc355013f90fea78d83d3a6c71f1d37ac07ecd5
 
 DEPGET := cd /tmp && GO111MODULE=on go get -v
-GOBUILD := GO111MODULE=on go build -v -trimpath
-GOINSTALL := GO111MODULE=on go install -v -trimpath
+GOBUILD := GO111MODULE=on go build -v
+GOINSTALL := GO111MODULE=on go install -v
 GOTEST := GO111MODULE=on go test -v
 
 GOFILES_NOVENDOR = $(shell find . -type f -name '*.go' -not -path "./vendor/*")