gcc: 4.9.2: Add patch to remove a wrong header

This commit adds a patch to gcc removing a unistd.h header include
in libgcc/config/nios2/linux-atomic.c

The file is built as part of GCC first stage (host-gcc-initial),
and so the header is not accesible. Given the header is not needed
it's fine to simply remove it.

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/gcc/4.9.2/920-libgcc-remove-unistd-header.patch

@@ -0,0 +1,12 @@
+Upstream status: In progress
+
+--- a/libgcc/config/nios2/linux-atomic.c
++++ b/libgcc/config/nios2/linux-atomic.c
+@@ -20,7 +20,6 @@
+ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+ <http://www.gnu.org/licenses/>.  */
+ 
+-#include <asm/unistd.h>
+ #define EFAULT  14
+ #define EBUSY   16
+ #define ENOSYS  38