misc/cgo/test: make issue5548 test pickier

If there is doubt about passing arguments correctly
(as there is in this test), there should be doubt about
getting the results back intact too. Using 0 and 1
(especially 0 for success) makes it easy to get a PASS
accidentally when the return value is not actually
being propagated. Use less common values.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews, r
https://golang.org/cl/141110043

misc/cgo/test/issue5548.go

@@ -14,13 +14,14 @@ import "C"
 //export issue5548FromC
 func issue5548FromC(s string, i int) int {
 	if len(s) == 4 && s == "test" && i == 42 {
-		return 1
+		return 12345
 	}
-	return 0
+	println("got", len(s), i)
+	return 9876
 }
 
 func test5548(t *testing.T) {
-	if C.issue5548_in_c() == 0 {
-		t.Fail()
+	if x := C.issue5548_in_c(); x != 12345 {
+		t.Errorf("issue5548_in_c = %d, want %d", x, 12345)
 	}
 }