libiberty: Add -Wshadow=local to warning flags (if supported).

libiberty/ChangeLog:

       * configure.ac (ac_libiberty_warn_cflags): Add -Wshadow=local.
       * configure: Regenerated.

From-SVN: r242396

libiberty/ChangeLog

@@ -1,3 +1,8 @@
+2016-11-06  Mark Wielaard  <mark@klomp.org>
+
+	* configure.ac (ac_libiberty_warn_cflags): Add -Wshadow=local.
+	* configure: Regenerated.
+
 2016-11-07  Jason Merrill  <jason@redhat.com>
 
 	* cp-demangle.c (is_fnqual_component_type): New.

libiberty/configure

@@ -4398,7 +4398,8 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 ac_libiberty_warn_cflags=
 save_CFLAGS="$CFLAGS"
 for real_option in -W -Wall -Wwrite-strings -Wc++-compat \
-			  -Wstrict-prototypes; do
+			  -Wstrict-prototypes \
+			  -Wshadow=local; do
   # Do the check with the no- prefix removed since gcc silently
   # accepts any -Wno-* option on purpose
   case $real_option in

libiberty/configure.ac

@@ -160,7 +160,8 @@ AC_SYS_LARGEFILE
 AC_PROG_CPP_WERROR
 
 ACX_PROG_CC_WARNING_OPTS([-W -Wall -Wwrite-strings -Wc++-compat \
-			  -Wstrict-prototypes], [ac_libiberty_warn_cflags])
+			  -Wstrict-prototypes \
+			  -Wshadow=local], [ac_libiberty_warn_cflags])
 ACX_PROG_CC_WARNING_ALMOST_PEDANTIC([], [ac_libiberty_warn_cflags])
 
 AC_PROG_CC_C_O