TBR: small fix for jni libraries on darwin

Change-Id: Ica809510262a925df729c584b567c9296afdd6ec
diff --git a/util/call.go b/util/call.go
index b0bd07a..ca4420f 100644
--- a/util/call.go
+++ b/util/call.go
@@ -20,7 +20,7 @@
 //   return malloc(sizeof(jvalue) * elements);
 // }
 //
-// static setJValueArrayElement(jvalue* arr, int index, jvalue val) {
+// static void setJValueArrayElement(jvalue* arr, int index, jvalue val) {
 //   arr[index] = val;
 // }
 //