runtime: make runtime-gdb.py tolerant of creatively-named gdb versions
runtime: make runtime-gdb.py tolerant of creatively-named gdb versions

"Fedora" and "Red Hat" are not numbers, it turns out.
Don't rely on version numbers, instead use a regexp to
handle variation across the 2 patterns thus far observed
for gdb-generated Go type names.

Change-Id: I18c81aa2848265a47daf1180d8f6678566ae3f19
Reviewed-on: https://go-review.googlesource.com/c/go/+/236280
Reviewed-by: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>
Run-TryBot: David Chase <ae171625adc8645b8b79b7e405a6da5aba5341e0@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

nawawi/go,nawawi/go,cloudflare/go,CAFxX/go,nawawi/go,akutz/go,akutz/go,nawawi/go,CAFxX/go,CAFxX/go,akutz/go,akutz/go,akutz/go,akutz/go,cloudflare/go,akutz/go,cloudflare/go,CAFxX/go,golang/go,CAFxX/go,golang/go,golang/go,cloudflare/go,golang/go,nawawi/go,CAFxX/go,nawawi/go,cloudflare/go,nawawi/go,nawawi/go,cloudflare/go,golang/go,CAFxX/go,golang/go,golang/go,cloudflare/go,CAFxX/go,akutz/go,cloudflare/go,golang/go