NetBSD's semaphores use the underlying lighweight process mechanism
(LWP) on NetBSD, rather than pthreads. This means the m.prodcid needs
to be set to the LWP ID rather than the pthread ID in order for unpark
notifications to get sent to the right place.
Introduce a new getProcID() method that selects the correct ID for the
platform.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/261742
This is a step toward updating libgo to 1.13. This adds the 1.13
version of the osinit function to Go code, and removes the
corresponding code from the C runtime. This should simplify future updates.
Some additional 1.13 code was brought in to simplify this change.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/191717
From-SVN: r275010