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>

 Signed-off-by: dank@kegel.com

 Raising the size of the hash table is a noticable win when linking 

 at least one large app.  

 There was a patch,

 http://sources.redhat.com/ml/binutils/2004-06/msg00165.html

 to do this dynamically.  No idea why that didn't make it in.

 So this tiny change to raise the default size is just

 a stopgap for now.

 --- binutils-2.17/bfd/hash.c.old	2006-03-02 23:01:39.000000000 -0800

 +++ binutils-2.17/bfd/hash.c	2006-03-02 23:01:58.000000000 -0800

 @@ -298,7 +298,7 @@

  */

  /* The default number of entries to use when creating a hash table.  */

 -#define DEFAULT_SIZE 4051

 +#define DEFAULT_SIZE 32749

  static size_t bfd_default_hash_table_size = DEFAULT_SIZE;

  /* Create a new hash table, given a number of entries.  */