[Go] proposals update

Building a better Go linker:
https://docs.google.com/document/d/1D13QhciikbdLtaI67U6Ble5d_1nsI4befE
d6_k1z91U/view

Coverage instrumentation for fuzzing:
https://github.com/golang/go/issues/14565

Scaling the Go page allocator:
https://github.com/golang/proposal/blob/master/design/35112-scaling-the-page-allocator.md

Make timers faster:
https://github.com/golang/go/issues/6239

Non-cooperative goroutine preemption:
https://github.com/golang/go/issues/24543