indeo3: avoid writes without necessary alignment in copy_cell()

Cells starting at a position aligned to 8 pixels but wider than
4 blocks are copied with 3 blocks per loop. This creates problems on the
next loop iterations since the routine copying 2 blocks requires the
same alignment on some architectures like ARM NEON.

libavcodec/indeo3.c

@@ -260,9 +260,7 @@ static int copy_cell(Indeo3DecodeContext *ctx, Plane *plane, Cell *cell)
             w -= 2;
             src += 8;
             dst += 8;
-        }
-
-        if (w >= 1) {
+        } else if (w >= 1) {
             ctx->hdsp.put_pixels_tab[2][0](dst, src, plane->pitch, h);
             w--;
             src += 4;