Represent C++ direct initializers as ParenListExprs before semantic analysis
instead of having a special-purpose function.

- ActOnCXXDirectInitializer, which was mostly duplication of
  AddInitializerToDecl (leading e.g. to PR10620, which Eli fixed a few days
  ago), is dropped completely.
- MultiInitializer, which was an ugly hack I added, is dropped again.
- We now have the infrastructure in place to distinguish between
  int x = {1};
  int x({1});
  int x{1};
-- VarDecl now has getInitStyle(), which indicates which of the above was used.
-- CXXConstructExpr now has a flag to indicate that it represents list-
   initialization, although this is not yet used.
- InstantiateInitializer was renamed to SubstInitializer and simplified.
- ActOnParenOrParenListExpr has been replaced by ActOnParenListExpr, which
  always produces a ParenListExpr. Placed that so far failed to convert that
  back to a ParenExpr containing comma operators have been fixed. I'm pretty
  sure I could have made a crashing test case before this.

The end result is a (I hope) considerably cleaner design of initializers.
More importantly, the fact that I can now distinguish between the various
initialization kinds means that I can get the tricky generalized initializer
test cases Johannes Schaub supplied to work. (This is not yet done.)

This commit passed self-host, with the resulting compiler passing the tests. I
hope it doesn't break more complicated code. It's a pretty big change, but one
that I feel is necessary.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150318 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index 4742bbf..8744f41 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -1646,10 +1646,9 @@
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildParenListExpr(SourceLocation LParenLoc,
-                                        MultiExprArg SubExprs,
-                                        SourceLocation RParenLoc) {
-    return getSema().ActOnParenOrParenListExpr(LParenLoc, RParenLoc, 
-                                               move(SubExprs));
+                                  MultiExprArg SubExprs,
+                                  SourceLocation RParenLoc) {
+    return getSema().ActOnParenListExpr(LParenLoc, RParenLoc, move(SubExprs));
   }
 
   /// \brief Build a new address-of-label expression.