[PATCH] move gdbarch object from objfile to per-BFD

[Tom Tromey]

>> I can add it.  The reason I did not is that, for whatever reason,
>> objfiles have not historically used accessors.  So, I preserved the
>> status quo in this respect.

Mark> Merely a suggestion.  If you considered it and decided against it
Mark> that's fine with me.

I'm not sure why, but even though the patch changed get_objfile_arch, I
failed to think of that as an accessor.  Weird; but I suppose since it
doesn't follow the usual gdb macro style.  Anyway, I'll shortly send an
updated patch that uses get_objfile_arch at all the spots that read the
field.  I left the writers alone, as there aren't many and we shouldn't
encourage more.

Tom