Update libvpx snapshot to v0.9.7-p1 (Cayuga).

source/libvpx/vp8/encoder/arm/armv6/vp8_variance8x8_armv6.asm

 ;
 ;  Copyright (c) 2011 The WebM project authors. All Rights Reserved.
 ;
 ;  Use of this source code is governed by a BSD-style license
 ;  that can be found in the LICENSE file in the root of the source
 ;  tree. An additional intellectual property rights grant can be found
 ;  in the file PATENTS.  All contributing project authors may
 ;  be found in the AUTHORS file in the root of the source tree.
 ;
 
 
     EXPORT  |vp8_variance8x8_armv6|
 
     ARM
 
     AREA ||.text||, CODE, READONLY, ALIGN=2
 
 ; r0    unsigned char *src_ptr
 ; r1    int source_stride
 ; r2    unsigned char *ref_ptr
 ; r3    int  recon_stride
 ; stack unsigned int *sse
 |vp8_variance8x8_armv6| PROC
 
     push    {r4-r10, lr}
+
+    pld     [r0, r1, lsl #0]
+    pld     [r2, r3, lsl #0]
+
     mov     r12, #8             ; set loop counter to 8 (=block height)
     mov     r4, #0              ; initialize sum = 0
     mov     r5, #0              ; initialize sse = 0
 
 loop
     ; 1st 4 pixels
     ldr     r6, [r0, #0x0]      ; load 4 src pixels
     ldr     r7, [r2, #0x0]      ; load 4 ref pixels
 
     mov     lr, #0              ; constant zero
 
     usub8   r8, r6, r7          ; calculate difference
+    pld     [r0, r1, lsl #1]
     sel     r10, r8, lr         ; select bytes with positive difference
     usub8   r9, r7, r6          ; calculate difference with reversed operands
+    pld     [r2, r3, lsl #1]
     sel     r8, r9, lr          ; select bytes with negative difference
 
     ; calculate partial sums
     usad8   r6, r10, lr         ; calculate sum of positive differences
     usad8   r7, r8, lr          ; calculate sum of negative differences
     orr     r8, r8, r10         ; differences of all 4 pixels
     ; calculate total sum
     add    r4, r4, r6           ; add positive differences to sum
     sub    r4, r4, r7           ; substract negative differences from sum
 
@@ skipping 36 matching lines @@
     ldr     r8, [sp, #32]       ; get address of sse
     mul     r1, r4, r4          ; sum * sum
     str     r5, [r8]            ; store sse
     sub     r0, r5, r1, ASR #6  ; return (sse - ((sum * sum) >> 6))
 
     pop     {r4-r10, pc}
 
     ENDP
 
     END