cmd/compile: add missing OASOP case in mayModifyPkgVar
CL 395541 made staticopy safe, stop applying the optimization once
seeing an expression that may modify global variables. However, it
misses the case for OASOP expression, causing the static init
mis-recognizes the modification and think it's safe.
Fixing this by adding missing OASOP case.
Fixes #66585
Change-Id: I603cec018d3b5a09825c14e1f066a0e16f8bde23
Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest
Reviewed-on: https://go-review.googlesource.com/c/go/+/575216 Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Than McIntosh <thanm@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>