All GL function calls fill out a C.struct_fnargs and drop it on the
work queue. The Start function drains the work queue and hands
over a batch of calls to C.process which runs them. This allows
multiple GL calls to be executed in a single cgo call.
A GL call is marked as blocking if it returns a value, or if it
takes a Go pointer. In this case the call will not return until
C.process sends a value on the retvalue channel.
Change-Id: I4c76b2a8ad55f57b0c98d200d0fb708d4634e042
Reviewed-on: https://go-review.googlesource.com/10452
Reviewed-by: Nigel Tao <nigeltao@golang.org>
068a51c195