test: update list of escape reasons

The escape_because.go test file (which tests the "because" escape
explainations printed by `-m -m`) cointains a machine-generated list
of all the escape reasons seen in the escape tests.

The list appears to be outdated; moreove a new escape reason was added
in CL 102895. This change re-generates the list.

Change-Id: Idc721c6bbfe9516895b5cf1e6d09b77deda5a3dd
Reviewed-on: https://go-review.googlesource.com/103375


Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>