[binutils-gdb/gdb-8.0-branch] Improve "'g' reply is is to long" error message

[sergiodj+buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT e72d662aba1bc92e141688ebb27f3948ec5d2997 ***

Author: Simon Marchi <simon.marchi@ericsson.com>
Branch: gdb-8.0-branch
Commit: e72d662aba1bc92e141688ebb27f3948ec5d2997

Improve "'g' reply is is to long" error message

... by adding the expected size, and the received size.  I found this
useful when debugging gdbarch/remote issues, since it gives a hint of
what gdb expects and what the remote sent.

gdb/ChangeLog:

	* remote.c (process_g_packet): Update error message.