cmd/link: support -bindnow option and permit use of "-Wl,-z,now"
This is a partial roll-forward of CL 473495, which was subsequently
reverted. The second half of CL 473495 will appear in a future CL.
In this patch we introduce a new Go linker "-bindnow" command line
flag, and update the Go command to permit the use of the -Wl,-z,now
option, to allow users to produce binaries that have immediate
binding.
Updates #45681.
Change-Id: Idd61b0d6597bcd37b16c343714c55a4ef6dfb534
Reviewed-on: https://go-review.googlesource.com/c/go/+/571416 Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>