runtime: change mcall to take a Go function value
For future work in bringing in the Go 1.8 GC, change the mcall
function to take a Go function value, which means that mcall can take
a closure rather than just a straight C function pointer.
As part of this change move kickoff from C to Go, which we want to do
anyhow so that we run the write barriers that it generates.
Reviewed-by: Than McIntosh <firstname.lastname@example.org>
6 files changed