[POWERPC] Add strncmp to arch/ppc

Commit 0119536cd314ef95553604208c25bc35581f7f0a added an assembly
version of strncmp to PowerPC.  However, it changed a common header
file between arch/ppc and arch/powerpc without adding strncmp to
arch/ppc.  This fixes that omission so that arch/ppc links again.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/ppc/lib/string.S b/arch/ppc/lib/string.S
index 84ed33a..927253b 100644
--- a/arch/ppc/lib/string.S
+++ b/arch/ppc/lib/string.S
@@ -121,6 +121,20 @@
 	beq	1b
 	blr
 
+_GLOBAL(strncmp)
+	PPC_LCMPI r5,0
+	beqlr
+	mtctr	r5
+	addi	r5,r3,-1
+	addi	r4,r4,-1
+1:	lbzu	r3,1(r5)
+	cmpwi	1,r3,0
+	lbzu	r0,1(r4)
+	subf.	r3,r0,r3
+	beqlr	1
+	bdnzt	eq,1b
+	blr
+
 _GLOBAL(strlen)
 	addi	r4,r3,-1
 1:	lbzu	r0,1(r4)