RFC: Readline 5.1 import

[Daniel Jacobowitz <drow at false dot org>]

I've locally imported readline 5.1 into src, replacing our older readline
4.3 import.  It requires only two small changes in gdb (both dealing with
the rename of rluser.texinfo -> rluser.texi); patch attached.  I've also
attached a diff between readline 5.1 + upstream patches 001-004, and
my imported directory; I don't know how else I can usefully present the
changes, since a diff from the previous version of readline is too huge to
be useful.

I've done my best to preserve every local change.  The local changes are
mainly for Cygwin, DJGPP, and MinGW32; I tested GNU/Linux, and did manual
testing on both Cygwin and MinGW32.  My last attempt to build a DJGPP GDB
took all day and failed horribly due to GCC bugs, so I'm afraid I can't
test the __MSDOS__ bits.  But they're pretty straightforward and I did
preserve all the local ones.

Does anyone mind my committing the merge?  I'll be glad to help straighten
out any problems arising from that.  If you'd like to test it first, let
me know; it's a bit of work to produce a patched source tree.

-- 
Daniel Jacobowitz
CodeSourcery

Attachment: readline51-local-changes.patch
Description: Text document

Attachment: readline51-gdb-doc-fixes.patch
Description: Text document