[RFA] Fix djgpp gdb-7.4 (and probably trunk) build failure in readline

["Pierre Muller" <pierre.muller@ics-cnrs.unistra.fr>]

  Jan Kratochvil suggested me to submit my patch directly to bug-readline
mailing list.

The bug appeared while trying to compile the nw GDB release 7.4
version on a Dos DJGPP target, that does not have
SIGWINCH signal. GDB now uses readline version 6.2,
so this patch is against this version of readline library.

>>>
>>> Starting here is the original post to gdb-patches:
>>>

DJGPP has no SIGWINCH
but despite this being checked by configure,
the code in readline/signal.c
is incompatible with a system that doesn't define SIGWINCH.
I found this problem while trying to compile GDB-7.4 sources for DJGPP.
Trunk source seems to be the same...

I don't know what is the master readline repository...
I am also unsure about proper ChangeLog entry for this...

Pierre Muller
GDB pascal language maintainer

ChangeLog entry:
2012-01-27  Pierre Muller  <muller@ics.u-strasbg.fr>

        * signals.c (_rl_block_sigwinch, _rl_release_sigwinch): Add
        conditional SIGWINCH around functions.

--- readline/signals.c  2011-05-12 01:38:39.000000000 +0200
+++ readline/signals.c.new      2012-01-27 17:47:06.837454200 +0100
@@ -580,6 +580,7 @@ _rl_release_sigint ()
   sigint_blocked = 0;
 }

+#ifdef SIGWINCH
 /* Cause SIGWINCH to not be delivered until the corresponding call to
    release_sigwinch(). */
 void
@@ -627,6 +628,7 @@ _rl_release_sigwinch ()

   sigwinch_blocked = 0;
 }
+#endif /* SIGWINCH */

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