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: ../../dev/crosstool-NG/ct-ng.trunk/patches/strace/4.5.17/120-fix-arm-bad-syscall.patch

-= BEGIN original header =-

diff -dur strace-4.5.16.orig/syscall.c strace-4.5.16/syscall.c

-= END original header =-

diff -durN strace-4.5.17.orig/syscall.c strace-4.5.17/syscall.c

--- strace-4.5.17.orig/syscall.c	2008-05-28 01:18:29.000000000 +0200

+++ strace-4.5.17/syscall.c	2008-10-24 21:30:13.000000000 +0200

@@ -1016,6 +1016,15 @@

 		/*

 		 * Note: we only deal with only 32-bit CPUs here.

 		 */

+

+		if (!(tcp->flags & TCB_INSYSCALL) &&

+		    (tcp->flags & TCB_WAITEXECVE)) {

+			/* caught a fake syscall from the execve's exit */

+			tcp->flags &= ~TCB_WAITEXECVE;

+			return 0;

+		}

+

+

 		if (regs.ARM_cpsr & 0x20) {

 			/*

 			 * Get the Thumb-mode system call number