x/sys/windows/svc/mgr: allow other ServiceType values in CreateService
x/sys/windows/svc/mgr: allow other ServiceType values in CreateService

Preserves SERVICE_WIN32_OWN_PROCESS as the default.

Fixes golang/go#14019

Change-Id: I764016c1b5ec5e1fe88ed39b9803754af966b2f3
Reviewed-on: https://go-review.googlesource.com/18760
Reviewed-by: Alex Brainman <54ba58c8441b5eff861de6b4e5ee46baf086b142@gmail.com>
Run-TryBot: Alex Brainman <54ba58c8441b5eff861de6b4e5ee46baf086b142@gmail.com>

multiplay/golang-sys,golang/sys,multiplay/golang-sys,golang/sys,golang/sys,multiplay/golang-sys,multiplay/golang-sys