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.
(transplanted from 1ba79f2126df8bd89120899a58f2d0bcc2e9c771)

 # Binary utilities menu

 menu "Binary utilities"

 choice

     bool

     prompt "Binary format:"

 if ARCH_USE_MMU

 config ARCH_BINFMT_ELF

     bool

     prompt "ELF"

     help

       This will make your system build ELF exectubales,

       suitable for architectures with an MMU.

 endif # ARCH_USE_MMU

 if ! ARCH_USE_MMU

 config ARCH_BINFMT_FLAT

     bool

     prompt "Flat"

     help

       This will build flat binaries, suitable for

       MMU-less architectures.

 #config ARCH_BINFMT_FDPIC

 #    bool

 #    prompt "FD_PIC ELF"

 #    help

 #      This will build FD_PIC ELF binaries, suitable for

 #      MMU-less architectures that still require to use

 #      shared libraries (FIXME).

 endif # ! ARCH_USE_MMU

 endchoice

 source config/binutils/binutils.in

 source config/binutils/elf2flt.in

 endmenu