cmd/compile: fix bug in defer wrapping

The defer wrapping feature added to the compiler's "order" phase
creates temporaries into which it copies defer arguments. If one of
these temps is large enough that we place it into the defer closure by
address (as opposed to by value), then the temp in question can't be
reused later on in the order phase, nor do we want a VARKILL
annotation for it at the end of the current block scope.

Test written by Cherry.

Updates #40724.

Change-Id: Iec7efd87ec5a3e3d7de41cdcc7f39c093ed1e815
Reviewed-on: https://go-review.googlesource.com/c/go/+/312869


Trust: Than McIntosh <thanm@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>