go/internal/gccgoimporter: fix up gccgo installation test

Change the TestInstallationImporter testpoint to query type
information for sort.Search instead of sort.Ints. The latter function
changed recently (1.16 timeframe), parameter "a" is now "x". A better
candidate for this sort of query is sort.Search, which has been stable
for a while.

Fixes #44425.

Change-Id: I314476eac0b0802f86f5cbce32195cab2926db83
Reviewed-on: https://go-review.googlesource.com/c/go/+/294290


Trust: Than McIntosh <thanm@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>