kernel/linux: fix using custom location

Currently, extract and patch are skipped as thus:
- using a custom directory of pre-installed headers
- a correctly named directory already exists

Otherwise, extract and patch are done.

The current second condition is wrong, because it allows the following
sequence to happen:
- a non-custom kernel is used
- a previous build only partially extracted the non-custom sources
- that p[revious build broke during extraction (eg. incomplete tarball...)
- a subsequent build will find a properly named directory, and will
thus skip extract and patch, which is wrong

Fix that by following the conditions in this table:

Type | Extract | Patch
----------------------+---------+-------
Pre-installed headers | N | N
custom directory | N | N
custom tarball | Y | N
mainstream tarball | Y | Y

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: David Holsgrove <david.holsgrove@xilinx.com>

Original patch from: ../crosstool-NG/ct-ng.trunk/patches/binutils/2.19/100-ppc64-pie.patch

-= BEGIN original header =-

Original patch from Gentoo:

gentoo/src/patchsets/binutils/2.19/03_all_binutils-2.15.92.0.2-ppc64-pie.patch

-= END original header =-

diff -durN binutils-2.19.1.orig/bfd/elf64-ppc.c binutils-2.19.1/bfd/elf64-ppc.c

--- binutils-2.19.1.orig/bfd/elf64-ppc.c	2008-10-09 14:18:24.000000000 +0200

+++ binutils-2.19.1/bfd/elf64-ppc.c	2009-03-08 11:56:59.000000000 +0100

@@ -11294,7 +11294,12 @@

 	      else if (!SYMBOL_REFERENCES_LOCAL (info, &h->elf)

 		       && !is_opd

 		       && r_type != R_PPC64_TOC)

-		outrel.r_info = ELF64_R_INFO (h->elf.dynindx, r_type);

+		{

+		  outrel.r_info = ELF64_R_INFO (h->elf.dynindx, r_type);

+		  if (h->elf.dynindx == -1

+		      && h->elf.root.type == bfd_link_hash_undefweak)

+		  memset (&outrel, 0, sizeof outrel);

+		}

 	      else

 		{

 		  /* This symbol is local, or marked to become local,