Add support for context-aware logging functions

Summary:
@public

Context-aware logging functions are an internal Yoga feature that will be used for Yoga’s JNI code.

It will be possible to specify a context when calculating layout, which will be passed on to baseline and measure functions. This will be a private feature.

Reviewed By: SidharthGuglani

Differential Revision: D14123482

fbshipit-source-id: 8ba3b6c493bf79fe09831f22d2b6da44f09e3d95

yoga/YGConfig.cpp

@@ -6,13 +6,21 @@
  */
 #include "YGConfig.h"
 
-YGConfig::YGConfig(YGLogger logger) : logger_{logger} {}
+YGConfig::YGConfig(YGLogger logger) {
+  logger_.noContext = logger;
+  loggerUsesContext_ = false;
+}
 
 void YGConfig::log(
     YGConfig* config,
     YGNode* node,
     YGLogLevel logLevel,
+    void* logContext,
     const char* format,
     va_list args) {
-  logger_(config, node, logLevel, format, args);
+  if (loggerUsesContext_) {
+    logger_.withContext(config, node, logLevel, logContext, format, args);
+  } else {
+    logger_.noContext(config, node, logLevel, format, args);
+  }
 }