package/go: fixing host go cross compilation

package/go: fixing host go cross compilation

Actually if GOHOSTOS == GOOS || GOHOSTARCH == GOARCH the go build system assume
it's not cross compiling and uses the same toolchain for both the host and the
target. This commit adds a patch to enable the explicit
GO_ASSUME_CROSSCOMPILING in go build system and updates to go package
accordingly.

Fixes:
http://autobuild.buildroot.net/results/3636b1ac5756a782fd7578186508aaf9d105e3e9/
http://autobuild.buildroot.net/results/25790dca7e19527bb360d7dfb325cd9cfc3b56cc/
and many more.

References:
https://github.com/golang/go/issues/25177
https://golang.org/cl/112156

Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com>
Signed-off-by: Anisse Astier <anisse@astier.eu>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>