[devel] Changed some "#if defined(" to "ifdef"
diff --git a/pngwtran.c b/pngwtran.c
index 5893410..cff30b4 100644
--- a/pngwtran.c
+++ b/pngwtran.c
@@ -1,7 +1,7 @@
 
 /* pngwtran.c - transforms the data in a row for PNG writers
  *
- * Last changed in libpng 1.4.0 [September 17, 2009]
+ * Last changed in libpng 1.4.0 [September 23, 2009]
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -26,7 +26,7 @@
    if (png_ptr == NULL)
       return;
 
-#if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
+#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
    if (png_ptr->transformations & PNG_USER_TRANSFORM)
       if (png_ptr->write_user_transform_fn != NULL)
         (*(png_ptr->write_user_transform_fn)) /* User write transform function */
@@ -40,48 +40,48 @@
              /*  png_byte pixel_depth;       bits per pixel (depth*channels) */
            png_ptr->row_buf + 1);      /* start of pixel data for row */
 #endif
-#if defined(PNG_WRITE_FILLER_SUPPORTED)
+#ifdef PNG_WRITE_FILLER_SUPPORTED
    if (png_ptr->transformations & PNG_FILLER)
       png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
          png_ptr->flags);
 #endif
-#if defined(PNG_WRITE_PACKSWAP_SUPPORTED)
+#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
    if (png_ptr->transformations & PNG_PACKSWAP)
       png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
-#if defined(PNG_WRITE_PACK_SUPPORTED)
+#ifdef PNG_WRITE_PACK_SUPPORTED
    if (png_ptr->transformations & PNG_PACK)
       png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
          (png_uint_32)png_ptr->bit_depth);
 #endif
-#if defined(PNG_WRITE_SWAP_SUPPORTED)
+#ifdef PNG_WRITE_SWAP_SUPPORTED
    if (png_ptr->transformations & PNG_SWAP_BYTES)
       png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
-#if defined(PNG_WRITE_SHIFT_SUPPORTED)
+#ifdef PNG_WRITE_SHIFT_SUPPORTED
    if (png_ptr->transformations & PNG_SHIFT)
       png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
          &(png_ptr->shift));
 #endif
-#if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
+#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
    if (png_ptr->transformations & PNG_SWAP_ALPHA)
       png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
-#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
    if (png_ptr->transformations & PNG_INVERT_ALPHA)
       png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
-#if defined(PNG_WRITE_BGR_SUPPORTED)
+#ifdef PNG_WRITE_BGR_SUPPORTED
    if (png_ptr->transformations & PNG_BGR)
       png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
-#if defined(PNG_WRITE_INVERT_SUPPORTED)
+#ifdef PNG_WRITE_INVERT_SUPPORTED
    if (png_ptr->transformations & PNG_INVERT_MONO)
       png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 }
 
-#if defined(PNG_WRITE_PACK_SUPPORTED)
+#ifdef PNG_WRITE_PACK_SUPPORTED
 /* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
  * row_info bit depth should be 8 (one pixel per byte).  The channels
  * should be 1 (this only happens on grayscale and paletted images).
@@ -202,7 +202,7 @@
 }
 #endif
 
-#if defined(PNG_WRITE_SHIFT_SUPPORTED)
+#ifdef PNG_WRITE_SHIFT_SUPPORTED
 /* Shift pixel values to take advantage of whole range.  Pass the
  * true number of bits in bit_depth.  The row should be packed
  * according to row_info->bit_depth.  Thus, if you had a row of
@@ -330,7 +330,7 @@
 }
 #endif
 
-#if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
+#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
 void /* PRIVATE */
 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
 {
@@ -416,7 +416,7 @@
 }
 #endif
 
-#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
 void /* PRIVATE */
 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 {
@@ -503,7 +503,7 @@
 }
 #endif
 
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+#ifdef PNG_MNG_FEATURES_SUPPORTED
 /* Undoes intrapixel differencing  */
 void /* PRIVATE */
 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)