Properly track l-paren of a CXXFucntionalCastExpr.

In addition to storing more useful information in the AST, this
fixes a semantic check in template instantiation which checks whether
the l-paren location is valid.

Fixes PR16903.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188495 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 5c1a27d..3eeb53e 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -2177,7 +2177,7 @@
     WarnE = this;
     if (const CXXFunctionalCastExpr *CXXCE =
             dyn_cast<CXXFunctionalCastExpr>(this)) {
-      Loc = CXXCE->getTypeBeginLoc();
+      Loc = CXXCE->getLocStart();
       R1 = CXXCE->getSubExpr()->getSourceRange();
     } else {
       const CStyleCastExpr *CStyleCE = cast<CStyleCastExpr>(this);