Fix #77963, #80314 and #81019. Added gtest-317, ..., gtest-320.
* class.cs (TypeContainer.CreateType): New public method. This is
now called before DefineType() to create the TypeBuilders.
(TypeContainer.DefineType): Don't create the TypeBuilder here; it
has already been created by CreateType().
(TypeContainer.DefineTypeBuilder): Renamed into CreateTypeBuilder();
don't resolve our base classes here; this has been moved into
DefineBaseTypes(). We're now called from CreateType().
(TypeContainer.DefineBaseTypes): New private method; resolve our
base classes here. We're now called from DefineType().
* rootcontext.cs
(RootContext.ResolveTree): Call TypeContainer.CreateType() on all
our types first to create all the TypeBuilders. After that, call
TypeContainer.DefineType() on all the types which'll resolve their
base classes and setup the resolve order.
svn path=/trunk/mcs/; revision=74709
