cmd/link/internal/ld: use linkerFlagSupported to check -Qunused-arguments

Rather than checking the linker name or its path for the string "clang",
use linkerFlagSupported to determine whether the -Qunused-arguments flag
may be passed to the linker.

Fixes #45241

Change-Id: I4c1e4d4ecba4cf5823e8f39cfda5d20404ebf513
Reviewed-on: https://go-review.googlesource.com/c/go/+/304692


Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>