Add concrete type overloads to PDBSymbol::findChildren().

Frequently you only want to iterate over children of a specific
type (e.g. functions).  Previously you would get back a generic
interface that allowed iteration over the base symbol type,
which you would have to dyn_cast<> each one of.  With this patch,
we allow the user to specify the concrete type as a template
parameter, and it will return an iterator which returns instances
of the concrete type directly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228960 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/DebugInfo/PDB/PDBSymbolAnnotation.h

@@ -23,6 +23,8 @@ public:
   PDBSymbolAnnotation(const IPDBSession &PDBSession,
                       std::unique_ptr<IPDBRawSymbol> Symbol);
 
+  DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Annotation)
+
   void dump(raw_ostream &OS, int Indent, PDB_DumpLevel Level) const override;
 
   FORWARD_SYMBOL_METHOD(getAddressOffset)
@@ -32,10 +34,6 @@ public:
   FORWARD_SYMBOL_METHOD(getSymIndexId)
   // FORWARD_SYMBOL_METHOD(getValue)
   FORWARD_SYMBOL_METHOD(getVirtualAddress)
-
-  static bool classof(const PDBSymbol *S) {
-    return S->getSymTag() == PDB_SymType::Annotation;
-  }
 };
 }