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>

From the uClibc ML archives:

    http://lists.uclibc.org/pipermail/uclibc/2011-June/045411.html

>From 364a3a9c576d604bed146efe0b8b33d2b81d4c64 Mon Sep 17 00:00:00 2001

From: Jason Woodward <jason.woodward@timesys.com>

Date: Sat, 11 Jun 2011 01:08:48 -0400

Subject: [PATCH 1/3] Conditionalize use libgcc_eh when libubacktrace is not enabled

Signed-off-by: Jason Woodward <jason.woodward@timesys.com>

---

 libubacktrace/Makefile.in |    2 +-

 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/libubacktrace/Makefile.in b/libubacktrace/Makefile.in

index f75f68b..880a8af 100644

--- a/libubacktrace/Makefile.in

+++ b/libubacktrace/Makefile.in

@@ -12,7 +12,7 @@ CFLAGS-libubacktrace := -DNOT_IN_libc -DIS_IN_libubacktrace $(SSP_ALL_CFLAGS)

 LDFLAGS-libubacktrace.so := $(LDFLAGS) $(top_builddir)lib/libdl-$(VERSION).so

-ifeq ($(CONFIG_ARM_EABI),y)

+ifeq ($(UCLIBC_HAS_BACKTRACE)$(CONFIG_ARM_EABI),yy)

 LIBGCC += $(shell $(CC) -print-file-name=libgcc_eh.a)

 endif

-- 

1.7.0.4