build.bash: use GOFLAGS -trimpath and enable PIE
build.bash: use GOFLAGS -trimpath and enable PIE

GOFLAGS exists since Go 1.11: https://golang.org/doc/go1.11

https://github.com/rfjakob/gocryptfs/pull/460

rfjakob/gocryptfs,rfjakob/gocryptfs,rfjakob/gocryptfs,rfjakob/gocryptfs