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 glibc-2.12.1.orig/localedata/locales/zh_TW glibc-2.12.1/localedata/locales/zh_TW

 --- glibc-2.12.1.orig/localedata/locales/zh_TW	2004-11-01 00:42:28.000000000 +0100

 +++ glibc-2.12.1/localedata/locales/zh_TW	2009-11-13 00:50:17.000000000 +0100

 @@ -1,7 +1,7 @@

  comment_char %

  escape_char /

  %

 -% Chinese language locale for Taiwan R.O.C.

 +% Chinese language locale for Taiwan

  % charmap: BIG5-CP950

  %

  % Original Author:

 @@ -17,7 +17,7 @@

  % Reference:	http://wwwold.dkuug.dk/JTC1/SC22/WG20/docs/n690.pdf

  LC_IDENTIFICATION

 -title      "Chinese locale for Taiwan R.O.C."

 +title      "Chinese locale for Taiwan"

  source     ""

  address    ""

  contact    ""

 @@ -25,7 +25,7 @@

  tel        ""

  fax        ""

  language   "Chinese"

 -territory  "Taiwan R.O.C."

 +territory  "Taiwan"

  revision   "0.2"

  date       "2000-08-02"

  %