Pass correct src and dst strides to ScalePlane_12

Fix https://github.com/AOMediaCodec/libavif/issues/715.

src/scale.c

diff --git a/src/scale.c b/src/scale.c
index 69438cb..944ca13 100644
--- a/src/scale.c
+++ b/src/scale.c
@@ -83,13 +83,17 @@
             const uint32_t dstW = (i == AVIF_CHAN_Y) ? dstWidth : dstUVWidth;
             const uint32_t dstH = (i == AVIF_CHAN_Y) ? dstHeight : dstUVHeight;
             if (image->depth > 8) {
-                uint16_t * srcPlane = (uint16_t *)srcYUVPlanes[i];
-                uint16_t * dstPlane = (uint16_t *)image->yuvPlanes[i];
-                ScalePlane_12(srcPlane, srcYUVRowBytes[i], srcW, srcH, dstPlane, image->yuvRowBytes[i], dstW, dstH, AVIF_LIBYUV_FILTER_MODE);
+                uint16_t * const srcPlane = (uint16_t *)srcYUVPlanes[i];
+                const uint32_t srcStride = srcYUVRowBytes[i] / 2;
+                uint16_t * const dstPlane = (uint16_t *)image->yuvPlanes[i];
+                const uint32_t dstStride = image->yuvRowBytes[i] / 2;
+                ScalePlane_12(srcPlane, srcStride, srcW, srcH, dstPlane, dstStride, dstW, dstH, AVIF_LIBYUV_FILTER_MODE);
             } else {
-                uint8_t * srcPlane = srcYUVPlanes[i];
-                uint8_t * dstPlane = image->yuvPlanes[i];
-                ScalePlane(srcPlane, srcYUVRowBytes[i], srcW, srcH, dstPlane, image->yuvRowBytes[i], dstW, dstH, AVIF_LIBYUV_FILTER_MODE);
+                uint8_t * const srcPlane = srcYUVPlanes[i];
+                const uint32_t srcStride = srcYUVRowBytes[i];
+                uint8_t * const dstPlane = image->yuvPlanes[i];
+                const uint32_t dstStride = image->yuvRowBytes[i];
+                ScalePlane(srcPlane, srcStride, srcW, srcH, dstPlane, dstStride, dstW, dstH, AVIF_LIBYUV_FILTER_MODE);
             }
 
             if (srcImageOwnsYUVPlanes) {
@@ -102,13 +106,17 @@
         avifImageAllocatePlanes(image, AVIF_PLANES_A);
 
         if (image->depth > 8) {
-            uint16_t * srcPlane = (uint16_t *)srcAlphaPlane;
-            uint16_t * dstPlane = (uint16_t *)image->alphaPlane;
-            ScalePlane_12(srcPlane, srcAlphaRowBytes, srcWidth, srcHeight, dstPlane, image->alphaRowBytes, dstWidth, dstHeight, AVIF_LIBYUV_FILTER_MODE);
+            uint16_t * const srcPlane = (uint16_t *)srcAlphaPlane;
+            const uint32_t srcStride = srcAlphaRowBytes / 2;
+            uint16_t * const dstPlane = (uint16_t *)image->alphaPlane;
+            const uint32_t dstStride = image->alphaRowBytes / 2;
+            ScalePlane_12(srcPlane, srcStride, srcWidth, srcHeight, dstPlane, dstStride, dstWidth, dstHeight, AVIF_LIBYUV_FILTER_MODE);
         } else {
-            uint8_t * srcPlane = srcAlphaPlane;
-            uint8_t * dstPlane = image->alphaPlane;
-            ScalePlane(srcPlane, srcAlphaRowBytes, srcWidth, srcHeight, dstPlane, image->alphaRowBytes, dstWidth, dstHeight, AVIF_LIBYUV_FILTER_MODE);
+            uint8_t * const srcPlane = srcAlphaPlane;
+            const uint32_t srcStride = srcAlphaRowBytes;
+            uint8_t * const dstPlane = image->alphaPlane;
+            const uint32_t dstStride = image->alphaRowBytes;
+            ScalePlane(srcPlane, srcStride, srcWidth, srcHeight, dstPlane, dstStride, dstWidth, dstHeight, AVIF_LIBYUV_FILTER_MODE);
         }
 
         if (srcImageOwnsAlphaPlane) {