Fix CQS signal readability-implicit-bool-conversion in xplat/yoga/java/jni (#2008)

Summary: Pull Request resolved: react/yoga#2008

Reviewed By: Daniel9z

Differential Revision: D115850221

Author: CppQualityWearables Bot

packages/react-native/ReactAndroid/src/main/jni/first-party/yogajni/jni/corefunctions.cpp

@@ -15,7 +15,7 @@ namespace {
 JavaVM* globalVm = nullptr;
 struct JavaVMInitializer {
   explicit JavaVMInitializer(JavaVM* vm) {
-    if (!vm) {
+    if (vm == nullptr) {
       logErrorMessageAndDie(
           "You cannot pass a NULL JavaVM to ensureInitialized");
     }