libgo: Fix go/runtime test failure on S390.

The tests run out of memory on 31-bit S390 systems because
it does not have split stacks.

From-SVN: r221681

libgo/go/runtime/chan_test.go

@@ -202,6 +202,11 @@ func TestNonblockRecvRace(t *testing.T) {
 	n := 10000
 	if testing.Short() {
 		n = 100
+	} else {
+		if runtime.GOARCH == "s390" {
+			// Test uses too much address space on 31-bit S390.
+			t.Skip("skipping long test on s390")
+		}
 	}
 	for i := 0; i < n; i++ {
 		c := make(chan int, 1)

libgo/go/runtime/map_test.go

@@ -243,7 +243,12 @@ func TestIterGrowWithGC(t *testing.T) {
 
 func testConcurrentReadsAfterGrowth(t *testing.T, useReflect bool) {
 	if runtime.GOMAXPROCS(-1) == 1 {
-		defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(16))
+		if runtime.GOARCH == "s390" {
+			// Test uses too much address space on 31-bit S390.
+			defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(8))
+		} else {
+			defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(16))
+		}
 	}
 	numLoop := 10
 	numGrowStep := 250