Add support for parsing and representing C++ constructor declarations.

Notes:
  - Constructors are never found by name lookup, so they'll never get
    pushed into any scope. Instead, they are stored as an 
    OverloadedFunctionDecl in CXXRecordDecl for easy overloading.
  - There's a new action isCurrentClassName that determines whether an
    identifier is the name of the innermost class currently being defined;
    we use this to identify the declarator-id grammar rule that refers to 
    a type-name. 
  - MinimalAction does *not* support parsing constructors.
  - We now handle virtual and explicit function specifiers.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@58499 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index 686aba2..3c6c91e 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -237,6 +237,7 @@
   case CXXRecord:           nCXXSUC++; break;
   // FIXME: Statistics for C++ decls.
   case CXXMethod:
+  case CXXConstructor:
   case CXXClassVar:
     break;
   }