os: avoid finalizer race in windows process object
os: avoid finalizer race in windows process object

If proc.Release is called concurrently, a handle will be double-freed.

Change-Id: I0c0c32e312e07bc8615e0bf9e9b691214444d8d5
Reviewed-on: https://go-review.googlesource.com/c/go/+/322510
Trust: Jason A. Donenfeld <e7e312fea4c2c1aad2bb075d739111890e1ce08b@zx2c4.com>
Run-TryBot: Jason A. Donenfeld <e7e312fea4c2c1aad2bb075d739111890e1ce08b@zx2c4.com>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

nawawi/go,nawawi/go,golang/go,CAFxX/go,golang/go,cloudflare/go,CAFxX/go,golang/go,nawawi/go,golang/go,CAFxX/go,cloudflare/go,cloudflare/go,CAFxX/go,cloudflare/go,nawawi/go,golang/go,CAFxX/go,cloudflare/go,nawawi/go,cloudflare/go,golang/go,CAFxX/go,nawawi/go,cloudflare/go,nawawi/go,nawawi/go,golang/go,cloudflare/go,CAFxX/go,CAFxX/go,golang/go