runtime: fix runtime gdb test with gdb v8.2

runtime: fix runtime gdb test with gdb v8.2

Previously, some of output from gdb matched with literal string, while
gdb v8.2 print the address of variable (e.g. map key and value) in
output.

This commit fix the regex in testing the output.

Fixes #27608

Change-Id: Ic3fe8280b9f93fda2799116804822616caa66beb
Reviewed-on: https://go-review.googlesource.com/135055
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>