cmd/compile: add code generation tests for sqrt intrinsics
cmd/compile: add code generation tests for sqrt intrinsics

Add "sqrt-intrisified" code generation tests for mips64 and 386, where
we weren't intrisifying math.Sqrt (see CL 96615 and CL 95916), and for
mips and amd64, which lacked sqrt intrinsics tests.

Change-Id: I0cfc08aec6eefd47f3cd7a5995a89393e8b7ed9e
Reviewed-on: https://go-review.googlesource.com/96716
Run-TryBot: Alberto Donizetti <90b16103a35511ced020676f3544f17117fb4c92@gmail.com>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

akutz/go,codestation/go,golang/go,josharian/go,nawawi/go,akutz/go,nawawi/go,golang/go,Cofyc/go,Cofyc/go,cloudflare/go,josharian/go,akutz/go,codestation/go,CAFxX/go,golang/go,josharian/go,codestation/go,Cofyc/go,golang/go,nawawi/go,nawawi/go,cloudflare/go,cloudflare/go,codestation/go,Cofyc/go,cloudflare/go,cloudflare/go,cloudflare/go,CAFxX/go,CAFxX/go,akutz/go,Cofyc/go,golang/go,golang/go,codestation/go,golang/go,CAFxX/go,CAFxX/go,CAFxX/go,josharian/go,Cofyc/go,nawawi/go,akutz/go,Cofyc/go,codestation/go,cloudflare/go,josharian/go,nawawi/go,codestation/go,CAFxX/go,nawawi/go,akutz/go,akutz/go,codestation/go,cloudflare/go,josharian/go,CAFxX/go,golang/go,josharian/go,josharian/go,nawawi/go,akutz/go,Cofyc/go