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 gcc-4.4.0.orig/gcc/configure gcc-4.4.0/gcc/configure

 --- gcc-4.4.0.orig/gcc/configure	2009-05-27 21:38:08.000000000 +0200

 +++ gcc-4.4.0/gcc/configure	2009-05-27 21:38:42.000000000 +0200

 @@ -22205,7 +22205,7 @@

  	tls_first_minor=14

  	tls_as_opt="-m64 -Aesame --fatal-warnings"

  	;;

 -  sh-*-* | sh[34]-*-*)

 +  sh-*-* | sh[34]*-*-*)

      conftest_s='

  	.section ".tdata","awT",@progbits

  foo:	.long	25

 diff -durN gcc-4.4.0.orig/gcc/configure.ac gcc-4.4.0/gcc/configure.ac

 --- gcc-4.4.0.orig/gcc/configure.ac	2009-05-27 21:38:08.000000000 +0200

 +++ gcc-4.4.0/gcc/configure.ac	2009-05-27 21:38:42.000000000 +0200

 @@ -2673,7 +2673,7 @@

  	tls_first_minor=14

  	tls_as_opt="-m64 -Aesame --fatal-warnings"

  	;;

 -  sh-*-* | sh[34]-*-*)

 +  sh-*-* | sh[34]*-*-*)

      conftest_s='

  	.section ".tdata","awT",@progbits

  foo:	.long	25