0026988: Fresh compiler warnings (VC++ 14, GCC 5.2.1, CLang 3.6.2)

Compiler warnings eliminated:

- VC++: potential use of uninitialized variable
- GCC: potential use of uninitialized variable [-Wmaybe-uninitialized], redundant const on return value [-Wignored-qualifiers]
- CLang: missing override specifier on overloaded virtual function [-Winconsistent-missing-override], function call within typeid() [-Wpotentially-evaluated-expression]

src/BRepOffset/BRepOffset_MakeOffset.cxx

@@ -4700,6 +4700,9 @@ Standard_Boolean CheckBiNormals
    Standard_Boolean& bRemove,
    const Standard_Boolean RemoveInvalidFaces)
 {
+  bKeep = Standard_True;
+  bRemove = Standard_False;
+
   Standard_Boolean bChecked;
   Standard_Integer aNbEdgesChecked;
   Standard_Real anAngle;
@@ -4792,8 +4795,6 @@ Standard_Boolean CheckBiNormals
   }
   //
   // decide whether to remove the split face or not
-  bKeep = Standard_True;
-  bRemove = Standard_False;
   //
   Standard_Integer  aNb = aMEInv.Extent();
   if (aNb == 0) {