runtime: convert netpoll to Go
The common code is converted, epoll and kqueue are converted.
Windows and solaris are still C.
LGTM=rsc
R=golang-codereviews, rsc, dave
CC=golang-codereviews, iant, khr, rsc
https://golang.org/cl/132910043
diff --git a/src/pkg/runtime/asm_386.s b/src/pkg/runtime/asm_386.s
index 3c46b40..87dd1fa 100644
--- a/src/pkg/runtime/asm_386.s
+++ b/src/pkg/runtime/asm_386.s
@@ -598,6 +598,9 @@
MOVL AX, ret+8(FP)
RET
+TEXT runtime·xchguintptr(SB), NOSPLIT, $0-12
+ JMP runtime·xchg(SB)
+
TEXT runtime·procyield(SB),NOSPLIT,$0-0
MOVL cycles+0(FP), AX
again:
