all: update vendored golang.org/x/tools
Pull in CL 593297:
f2d2ebe4 go/analysis/passes/buildtag: retire Go 1.15 support
Along with other changes that have landed into x/tools.
This fixes a vet failure reported on longtest builders.
For #66092.
Change-Id: I549cc3f8e2c2033fe961bf014ff8cc1998021538
Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest
Reviewed-on: https://go-review.googlesource.com/c/go/+/593376
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Bypass: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>