[go] Increase go_os_test timeout to 5m

FIDL is currently undergoing a wire format migration. As part
of this, a transformer is used between the old and new wire
format which adds extra latency. This has the effect of slowing
down the go_os_test on the ASAN build enough that it exceeds
the existing timeout.

A previous CL (I7fa19fbe348492617abd796a328cb7a9f38e0415)
increased the timeout to 3m, but there is a long tail
of runs which take significantly longer than 3m. CQ was run 5
times in a row with a 5m timeout, with the test passing each
time.

This unblocks:
https://fuchsia-review.googlesource.com/c/fuchsia/+/574261

Change-Id: Ifa15b9680a2d18ec46c705d24344227e3b70ee8f
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/go/+/583205
Reviewed-by: Tamir Duberstein <tamird@google.com>
Commit-Queue: Benjamin Prosnitz <bprosnitz@google.com>
diff --git a/meta/go_os_test.cmx b/meta/go_os_test.cmx
index d29b715..17ace76 100644
--- a/meta/go_os_test.cmx
+++ b/meta/go_os_test.cmx
@@ -2,7 +2,7 @@
     "program": {
         "args": [
             "--test.timeout",
-            "3m"
+            "5m"
         ],
         "binary": "test/go_os_test"
     },