Enable -Wextra in C++ builds (#1294)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1294

X-link: https://github.com/facebook/react-native/pull/37383

Add -Wextra to the build, and fixup some more instances of -Wunused-parameter that it sufaces which were not automatically fixable.

Reviewed By: javache

Differential Revision: D45772846

fbshipit-source-id: 29bf71006f63161521fe5869c3a7d8bf7aae9c81

yoga/Yoga.cpp

@@ -42,8 +42,8 @@ static int YGDefaultLog(
 #ifdef ANDROID
 #include <android/log.h>
 static int YGAndroidLog(
-    const YGConfigRef config,
-    const YGNodeRef node,
+    const YGConfigRef /*config*/,
+    const YGNodeRef /*node*/,
     YGLogLevel level,
     const char* format,
     va_list args) {