[POWERPC] Fix ARCH=ppc builds
[POWERPC] Fix ARCH=ppc builds

The recent signal rework broke ARCH=ppc builds with the following
error:

CC      arch/powerpc/kernel/signal.o
arch/powerpc/kernel/signal.c: In function Âdo_signalÂ:
arch/powerpc/kernel/signal.c:142: error: implicit declaration of
function Âset_dabrÂ
make[1]: *** [arch/powerpc/kernel/signal.o] Error 1

This fixes it by including a function prototype in asm-ppc/system.h.

Acked-by: Kumar Gala <383ef5577c6e1178b93f59ec8d0936f76d2a98c4@kernel.crashing.org>
Signed-off-by: Josh Boyer <94755a79aca753e683bb6d0e796d473b797056eb@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas