V-Table Fixup Declaration
<vtfixupDecl> ::= .vtfixup [<int32>] <vtfixupAttr> at <id> <vtfixupAttr> ::= /* EMPTY */ <vtfixupAttr> int32 <vtfixupAttr> int64 <vtfixupAttr> fromunmanaged <vtfixupAttr> callmostderived