Update for LLVM API change to remove discriminator tracking from DILexicalBlock (in favor of DILexicalBlockFile - where a default arg is used to avoid the need for API churn of those callers)

llvm-svn: 216240
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index d621755..0b20f54 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -2596,8 +2596,7 @@
   llvm::DIDescriptor D = DBuilder.createLexicalBlock(
       llvm::DIDescriptor(LexicalBlockStack.empty() ? nullptr
                                                    : LexicalBlockStack.back()),
-      getOrCreateFile(CurLoc), getLineNumber(CurLoc), getColumnNumber(CurLoc),
-      0);
+      getOrCreateFile(CurLoc), getLineNumber(CurLoc), getColumnNumber(CurLoc));
   llvm::MDNode *DN = D;
   LexicalBlockStack.push_back(DN);
 }