[PATCH 0/7] Implement gdbarch_gdb_signal_{to,from}_target

[Sergio Durigan Junior <sergiodj@redhat.com>]

This is the second attempt to implement gdbarch_gdb_signal_to_target,
but this time with the additional implementation of
gdbarch_gdb_signal_from_target (a MIPS-only method so far).

The first attempt is here:

<http://sourceware.org/ml/gdb-patches/2013-07/msg00002.html>

The notable changes are:

- linux-tdep.c now registers the generic converters itself, thus
  eliminating the need for every target to do so.

- Comment about SIGSWI on ARM (discussion here:
  <http://sourceware.org/ml/gdb-patches/2013-07/msg00002.html>).

- Rewrite MIPS implementation of gdbarch_gdb_signal_from_target.
  Remove "enum mips_signals".

Hopefully everything is right now.  If the patch is approved, I intend
to commit it as a whole, instead of each chunk separately.

Thanks.