runtime: work around escaping closure in export_test.go

When compiling runtime, it is not allowed for local variables
    and closures to be heap allocated. In one test, there is a go
    statement with a closure. In the gc compiler, it distinguishes
    capturing variable by value vs. by address, and rewrites it to
    passing the captured values as arguments. Currently we don't
    have this, and the escape analysis decides to heap allocate the
    closure and also the captured variables, which is not allowed.
    Work around it by passing the variables explicitly.
    
    This is in preparation of turning on escape analysis for the
    runtime.
    
    Reviewed-on: https://go-review.googlesource.com/86245

From-SVN: r256419

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-5cae6a4e0849a3586ee7ce9c915c1520a17db982
+c18c6bd80e0995827ad3396eb1c2401451de88fd
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/runtime/export_test.go

@@ -123,15 +123,15 @@ func RunSchedLocalQueueEmptyTest(iters int) {
 	// can lead to underutilization (both runnable Gs and idle Ps coexist
 	// for arbitrary long time).
 	done := make(chan bool, 1)
-	p := new(p)
+	_p_ := new(p)
 	gs := make([]g, 2)
 	ready := new(uint32)
 	for i := 0; i < iters; i++ {
 		*ready = 0
 		next0 := (i & 1) == 0
 		next1 := (i & 2) == 0
-		runqput(p, &gs[0], next0)
-		go func() {
+		runqput(_p_, &gs[0], next0)
+		go func(done chan bool, p *p, ready *uint32, next0, next1 bool) {
 			for atomic.Xadd(ready, 1); atomic.Load(ready) != 2; {
 			}
 			if runqempty(p) {
@@ -139,13 +139,13 @@ func RunSchedLocalQueueEmptyTest(iters int) {
 				throw("queue is empty")
 			}
 			done <- true
-		}()
+		}(done, _p_, ready, next0, next1)
 		for atomic.Xadd(ready, 1); atomic.Load(ready) != 2; {
 		}
-		runqput(p, &gs[1], next1)
-		runqget(p)
+		runqput(_p_, &gs[1], next1)
+		runqget(_p_)
 		<-done
-		runqget(p)
+		runqget(_p_)
 	}
 }