libc/uClibc: fix building on system with recent glibc

While trying to build a toolchain with ct-ng 1.5.0,
arm-unknown-linux-uclibcgnueabi target,
I get the following error:

[INFO ] Installing C library headers
[EXTRA] Copying sources to build dir
[EXTRA] Applying configuration
[EXTRA] Building headers
[EXTRA] Installing headers
[ERROR] extra/scripts/unifdef.c:209: error: conflicting types for 'getline'
[ERROR] make[2]: *** [extra/scripts/unifdef] Error 1
[ERROR] Build failed in step 'Installing C library headers'

The following patch solves the problem.
(It's a backport of this uClibc commit:
http://git.uclibc.org/uClibc/commit/?id=49e81cada73616864b9b31df0aeb6961c30f5a6e
)

[--SNIP from another mail--]
AFAIK this is a problem since glibc 2.10.

--- gdb-6.1.1-dist/readline/configure	2003-05-27 18:29:47.000000000 -0500

+++ gdb-6.1.1/readline/configure	2004-08-09 14:20:23.000000000 -0500

@@ -6249,7 +6249,12 @@

 echo "$as_me:$LINENO: checking for mbstate_t" >&5

+echo $ECHO_N "bash_cv_have_mbstate_t=$bash_cv_have_mbstate_t" >&6

 echo $ECHO_N "checking for mbstate_t... $ECHO_C" >&6

+if test "${bash_cv_have_mbstate_t+set}" != set; then

+  bash_cv_have_mbstate_t=yes

+  echo $ECHO_N "WARNING!! forcing to yes!!! $ECHO_C" >&6

+fi

 if test "${bash_cv_have_mbstate_t+set}" = set; then

   echo $ECHO_N "(cached) $ECHO_C" >&6

 else