What about check the bfd_arch_info before load the solib?

[Hui Zhu <teawater at gmail dot com>]

Hi guys,

In cross-compile remote debug environment, the gdb will load the solib
of local host if user doesn't set sysroot or something.
Load the wrong lib will make gdb get error.

I think maybe we can add some check code to check if the bfd_arch_info
of this solib is same with the current_gdbarch before load this solib
in.
If not same, output a warning to let user set gdb to load right lib.

What do you think about it?

Thanks,
Hui