* is_objfile_owned
* set_owner (objfile and gdbarch overloads)
* objfile and arch getters
Rename the fields in main_type to ensure no other code accesses them
directly. As usual, we can't make them actually private, but giving
them the `m_` prefix will help making sure they are not accessed when
not supposed to, by convention.
Remove the TYPE_OWNER macro to ensure no code uses the type_owner struct
directly.