[libiberty] Avoid compiler warnings in stack-limit.c

[Tristan Gingold]

Hi,

there are some systems on which getrlimit/setrlimit are not available, and 
compiling stack-limit.c on these systems generates a warning.
Cleaned up with this patch.

Tested while building gcc for ia64-hp-openvms on x86_64-darwin.

Ok for trunk ?

Tristan.

libiberty/
2012-03-30  Tristan Gingold  <ging...@adacore.com>

        * stack-limit.c: Includes ansidecl.h.
        (stack_limit_increase): Add ATTRIBUTE_UNUSED

diff --git a/libiberty/stack-limit.c b/libiberty/stack-limit.c
index e64cac2..82c3d44 100644
--- a/libiberty/stack-limit.c
+++ b/libiberty/stack-limit.c
@@ -34,6 +34,7 @@ Attempt to increase stack size limit to @var{pref} bytes if 
possible.
 */
 
 #include "config.h"
+#include "ansidecl.h"
 
 #ifdef HAVE_STDINT_H
 #include <stdint.h>
@@ -43,7 +44,7 @@ Attempt to increase stack size limit to @var{pref} bytes if 
possible.
 #endif
 
 void
-stack_limit_increase (unsigned long pref)
+stack_limit_increase (unsigned long pref ATTRIBUTE_UNUSED)
 {
 #if defined(HAVE_SETRLIMIT) && defined(HAVE_GETRLIMIT) \
     && defined(RLIMIT_STACK) && defined(RLIM_INFINITY)