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.

 --- gcc-4.1.0/libstdc++-v3/include/ext/rope.mps	2006-03-24 01:49:51 +0100

 +++ gcc-4.1.0/libstdc++-v3/include/ext/rope	2006-03-24 01:49:37 +0100

 @@ -59,6 +59,9 @@

  #include <bits/allocator.h>

  #include <ext/hash_fun.h>

 +/* cope w/ index defined as macro, SuSv3 proposal */

 +#undef index

 +

  # ifdef __GC

  #   define __GC_CONST const

  # else

 --- gcc-4.1.0/libstdc++-v3/include/ext/ropeimpl.h.mps	2006-03-24 01:50:04 +0100

 +++ gcc-4.1.0/libstdc++-v3/include/ext/ropeimpl.h	2006-03-24 01:50:28 +0100

 @@ -53,6 +53,9 @@

  #include <ext/memory> // For uninitialized_copy_n

  #include <ext/numeric> // For power

 +/* cope w/ index defined as macro, SuSv3 proposal */

 +#undef index

 +

  namespace __gnu_cxx

  {

    using std::size_t;