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)

 diff -dur strace-4.5.15.orig/net.c strace-4.5.15/net.c

 --- strace-4.5.15.orig/net.c	2006-12-13 20:57:23.000000000 +0100

 +++ strace-4.5.15/net.c	2007-07-14 19:29:36.000000000 +0200

 @@ -800,8 +800,12 @@

  #ifdef SOL_PACKET

  static const struct xlat sockpacketoptions[] = {

 +#if defined(PACKET_ADD_MEMBERSHIP)

  	{ PACKET_ADD_MEMBERSHIP,	"PACKET_ADD_MEMBERSHIP"	},

 +#endif

 +#if defined(PACKET_DROP_MEMBERSHIP)

  	{ PACKET_DROP_MEMBERSHIP,	"PACKET_DROP_MEMBERSHIP"},

 +#endif

  #if defined(PACKET_RECV_OUTPUT)

  	{ PACKET_RECV_OUTPUT,		"PACKET_RECV_OUTPUT"	},

  #endif