This reverts commit 168eb9cf.

CL 47831 fixes the issue with plugins on ARMv5, so we can re-enable the test.

Updates #19674.

Change-Id: Idcb29f93ffb0460413f1fab5bb82fa2605795038
Reviewed-on: https://go-review.googlesource.com/47834Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>