runtime: implement Goexit

This is needed for full support for the testing package

testdata/recover.go

@@ -1,5 +1,10 @@
 package main
 
+import (
+	"runtime"
+	"time"
+)
+
 func main() {
 	println("# simple recover")
 	recoverSimple()
@@ -22,6 +27,9 @@ func main() {
 
 	println("\n# defer panic")
 	deferPanic()
+
+	println("\n# runtime.Goexit")
+	runtimeGoexit()
 }
 
 func recoverSimple() {
@@ -104,6 +112,17 @@ func deferPanic() {
 	println("defer panic")
 }
 
+func runtimeGoexit() {
+	go func() {
+		defer func() {
+			println("Goexit deferred function, recover is nil:", recover() == nil)
+		}()
+
+		runtime.Goexit()
+	}()
+	time.Sleep(time.Millisecond)
+}
+
 func printitf(msg string, itf interface{}) {
 	switch itf := itf.(type) {
 	case string:

testdata/recover.txt

@@ -27,3 +27,6 @@ recovered: panic 2
 # defer panic
 defer panic
 recovered from deferred call: deferred panic
+
+# runtime.Goexit
+Goexit deferred function, recover is nil: true