all: avoid awkward wording from CL 236857

CL 236857 removed all uses of whitelist/blacklist, which is great.
But it substituted awkward phrasing using allowlist/blocklist,
especially as verbs or participles. This CL uses more standard English,
like "allow the function" or "blocked functions" instead of
"allowlist the function" or "blocklisted functions".

Change-Id: I9106a2fdbd62751c4cbda3a77181358a8a6d0f13
Reviewed-on: https://go-review.googlesource.com/c/go/+/236917


Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>