runtime: switch state back to Grunning after recovery

Fixes #733.

R=r
CC=golang-dev
https://golang.org/cl/958041

src/pkg/runtime/mgc0.c

@@ -128,6 +128,7 @@ mark(void)
 		case Gdead:
 			break;
 		case Grunning:
+		case Grecovery:
 			if(gp != g)
 				throw("mark - world not stopped");
 			scanstack(gp);
@@ -135,7 +136,6 @@ mark(void)
 		case Grunnable:
 		case Gsyscall:
 		case Gwaiting:
-		case Grecovery:
 			scanstack(gp);
 			break;
 		}

src/pkg/runtime/proc.c

@@ -248,7 +248,7 @@ readylocked(G *g)
 	}
 
 	// Mark runnable.
-	if(g->status == Grunnable || g->status == Grunning)
+	if(g->status == Grunnable || g->status == Grunning || g->status == Grecovery)
 		throw("bad g->status in ready");
 	g->status = Grunnable;
 
@@ -472,6 +472,7 @@ scheduler(void)
 			// before it tests the return value.)
 			gp->sched.sp = getcallersp(d->sp - 2*sizeof(uintptr));
 			gp->sched.pc = d->pc;
+			gp->status = Grunning;
 			free(d);
 			gogo(&gp->sched, 1);
 		}