cmd/go: add -shared to darwin/arm{,64} default build mode
Buildmode c-archive now supports position independent code for
darwin/arm (in addition to darwin/arm64). Make PIC (-shared) the
default for both platforms in the default buildmode.
Without this change, gomobile will go install the standard library
into its separate package directory without PIC support.
Also add -shared to darwin/arm64 in buildmode c-archive, for
symmetry (darwin/arm64 always generates position independent code).
Fixes #15519
Change-Id: If27d2cbea8f40982e14df25da2703cbba572b5c6
Reviewed-on: https://go-review.googlesource.com/22920 Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>