runtime: check for errors returned by windows sema calls

runtime: check for errors returned by windows sema calls

Add checks for failure of CreateEvent, SetEvent or
WaitForSingleObject. Any failures are considered fatal and
will throw() after printing an informative message.

Updates #16646

Change-Id: I3bacf9001d2abfa8667cc3aff163ff2de1c99915
Reviewed-on: https://go-review.googlesource.com/26655
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>