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: gentoo/src/patchsets/glibc/2.9/6018_all_alpha-glibc-2.8-cache-shape.patch

-= BEGIN original header =-

older verisons of glibc would build dl-sysdep as shared-only and dl-support as

static-only.  alpha hooks in a cache variable via dl-auxv.h.  newer versions of

glibc build dl-sysdep as both shared and static which means we now have symbol

duplication for static builds with dl-sysdep and dl-support.  since dl-sysdep

is both shared/static, there is no point in hooking dl-support anymore, so we

can punt it.

-= END original header =-

diff -durN glibc-2_9.orig/sysdeps/unix/sysv/linux/alpha/dl-support.c glibc-2_9/sysdeps/unix/sysv/linux/alpha/dl-support.c

--- glibc-2_9.orig/sysdeps/unix/sysv/linux/alpha/dl-support.c	2007-03-13 22:25:16.000000000 +0100

+++ glibc-2_9/sysdeps/unix/sysv/linux/alpha/dl-support.c	2009-02-02 22:01:37.000000000 +0100

@@ -1,1 +1,0 @@

-#include "dl-auxv.h"