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)

 # powerpc and powerpc64 common options

 if ARCH_powerpc || ARCH_powerpc64

 config ARCH_POWERPC_SPE

     bool

     prompt "Enable SPE support"

     default n

     help

       Add support for the Signal Processing Engine.  This will set up

       the toolchain so that it supports the SPE ABI extensions. This

       mainly targets Freescale e500 processors.

       Setting this option will append "spe" to the end of your target

       tuple name (e.g., powerpc-e500v2-linux-gnuspe) so that the gcc

       configure/build system will know to include SPE ABI support.

       It will also automatically add "-mabi=spe -mspe" to your

       TARGET_CFLAGS, and "--enable-e500_double" to your CC_EXTRA_CONFIG,

       so you do not need to explicitly add them.

 endif # ARCH_powerpc || ARCH_powerpc64