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>

diff -durN binutils-2.20.1.orig/ld/ldmain.c binutils-2.20.1/ld/ldmain.c

--- binutils-2.20.1.orig/ld/ldmain.c	2010-08-17 19:32:13.000000000 +0200

+++ binutils-2.20.1/ld/ldmain.c	2010-08-17 19:32:15.000000000 +0200

@@ -262,6 +262,7 @@

   link_info.allow_undefined_version = TRUE;

   link_info.keep_memory = TRUE;

+  link_info.new_dtags = TRUE;

   link_info.combreloc = TRUE;

   link_info.strip_discarded = TRUE;

   link_info.emit_hash = TRUE;