* stabsread.c (multiply_defined_struct): New complaint.

* stabsread.c (multiply_defined_struct): New complaint.
(read_struct_type): If the type we were passed isn't empty, or
incomplete, don't read the new struct type into it; complain,
and return the original type unchanged.  Take a new `type_code'
argument, which is the type code for the new type.
(read_type): Rather than storing the type's type code here, pass
it as an argument to read_struct_type, and let that take care of
storing it.  That way, we don't overwrite the original type code,
so read_struct_type can use it to decide whether we're overwriting
something we shouldn't.
(complain_about_struct_wipeout): New function.