This libgo patch changes the go tool to permit the AR environment
variable to include options. This mirrors the way it already handles
the CC environment variable.
This ports
https://go.dev/cl/526275 to the gofrontend repo.
This is needed for gccgo testing because the top-level GCC Makefile
now passes a --plugin option to ar if it supports one.
Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu. Committed
to mainline.
Ian