Fix warnings reported by -Wshadow: Part2b: more from av1 directory

From code only part of nextgenv2 (and not aomedia)

Change-Id: I21f7478a59d525dff23747efe5238ded16b743d2
diff --git a/av1/av1_cx_iface.c b/av1/av1_cx_iface.c
index d815ca7..fae7d04 100644
--- a/av1/av1_cx_iface.c
+++ b/av1/av1_cx_iface.c
@@ -871,7 +871,6 @@
   index_sz = 2 + (mag + 1) * (ctx->pending_frame_count - 1);
   if (ctx->pending_cx_data_sz + index_sz < ctx->cx_data_sz) {
     uint8_t *x = ctx->pending_cx_data + ctx->pending_cx_data_sz;
-    int i, j;
 #ifdef TEST_SUPPLEMENTAL_SUPERFRAME_DATA
     uint8_t marker_test = 0xc0;
     int mag_test = 2;     // 1 - 4
@@ -890,6 +889,7 @@
     *x++ = marker;
     for (i = 0; i < ctx->pending_frame_count - 1; i++) {
       unsigned int this_sz;
+      int j;
 
       assert(ctx->pending_frame_sizes[i] > 0);
       this_sz = (unsigned int)ctx->pending_frame_sizes[i] - 1;