Rename BinaryRef::isBinary to more descriptive DataIsHexString.

And add a doxygen comment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183350 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Object/YAML.cpp b/lib/Object/YAML.cpp
index b33cf34..cf6e616 100644
--- a/lib/Object/YAML.cpp
+++ b/lib/Object/YAML.cpp
@@ -51,7 +51,7 @@
 }
 
 void BinaryRef::writeAsBinary(raw_ostream &OS) const {
-  if (isBinary) {
+  if (!DataIsHexString) {
     OS.write((const char *)Data.data(), Data.size());
     return;
   }