cmd/link: fix TestTrampoline symbol name check on PPC64
CL 603736 added a check looking for a specific trampoline symbol
name. PPC64 uses a slightly different name for the trampoline,
update the test to accept both.
Change-Id: I177dadb25d82bc3ffeb7530d7ab865482d907d34
Reviewed-on: https://go-review.googlesource.com/c/go/+/621455 Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Paul Murphy <murp@ibm.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Pratt <mpratt@google.com>