rate: skip TestLongRunningQPS on OpenBSD
rate: skip TestLongRunningQPS on OpenBSD

time.Sleep is significantly oversleeping on OpenBSD, rendering this
test invalid.  Skip until that's resolved.

Updates #14183.

Change-Id: Ib0b79d198a0600454c5f74383d9933a2c05ddd2f
Reviewed-on: https://go-review.googlesource.com/19171
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/time