arm: Move a png_debug statement to its correct place

It should be placed immediately after all variable declarations.
diff --git a/arm/palette_neon_intrinsics.c b/arm/palette_neon_intrinsics.c
index b4d1fd2..00ddcef 100644
--- a/arm/palette_neon_intrinsics.c
+++ b/arm/palette_neon_intrinsics.c
@@ -30,8 +30,6 @@
    int num_trans = png_ptr->num_trans;
    int i;
 
-   png_debug(1, "in png_riffle_palette_neon");
-
    /* Initially black, opaque. */
    uint8x16x4_t w = {{
       vdupq_n_u8(0x00),
@@ -40,6 +38,8 @@
       vdupq_n_u8(0xff),
    }};
 
+   png_debug(1, "in png_riffle_palette_neon");
+
    /* First, riffle the RGB colours into an RGBA8 palette.
     * The alpha component is set to opaque for now.
     */