go: log build id computations

go writes build-specific ids into binaries it produces
and has a custom system for calculating them from
file hashes, environment variables and other inputs
(not that dissimilar to sstate cache, actually). This can
go wrong :) in various ways (for purposes of reproducibility
in particular), so this enables useful logs to see what
happens and why.

(From OE-Core rev: a587be1d18fc55fe57d1aa5aa7c9e26af887109e)

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/go.bbclass

@@ -2,6 +2,8 @@ inherit goarch
 
 GO_PARALLEL_BUILD ?= "${@oe.utils.parallel_make_argument(d, '-p %d')}"
 
+export GODEBUG = "gocachehash=1"
+
 GOROOT:class-native = "${STAGING_LIBDIR_NATIVE}/go"
 GOROOT:class-nativesdk = "${STAGING_DIR_TARGET}${libdir}/go"
 GOROOT = "${STAGING_LIBDIR}/go"

meta/recipes-devtools/go/go-common.inc

@@ -37,6 +37,8 @@ export GO386 ?= "${TARGET_GO386}"
 export GOMIPS ?= "${TARGET_GOMIPS}"
 export GOROOT_FINAL ?= "${libdir}/go"
 
+export GODEBUG = "gocachehash=1"
+
 do_compile:prepend() {
 	BUILD_CC=${BUILD_CC}
 }