os/signal: disable GNU readline to deflake TestTerminalSignal
Fixes #55903.
Change-Id: I992865277fb6526929d6c7db2b3b8d22ca0760f2
GitHub-Last-Rev:
fc6f28e17c3d6c5f16f1cc047e42ac0ceb60e769
GitHub-Pull-Request: golang/go#55904
Reviewed-on: https://go-review.googlesource.com/c/go/+/435735
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>