Changed `BaseClassSpecifier` to inherit from `DeclarationBase`.
Changed `BaseClassSpecifier` to inherit from `DeclarationBase`.

mono/CppSharp,ddobrev/CppSharp,zillemarco/CppSharp,ddobrev/CppSharp,zillemarco/CppSharp,mono/CppSharp,mono/CppSharp,ddobrev/CppSharp,zillemarco/CppSharp,ddobrev/CppSharp,mono/CppSharp,ddobrev/CppSharp,mono/CppSharp,mono/CppSharp,zillemarco/CppSharp,zillemarco/CppSharp