Update libjpeg-turbo to 1.2.

jpeglib.h

Index: jpeglib.h
===================================================================
--- jpeglib.h	(revision 111873)
+++ jpeglib.h	(working copy)
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 1991-1998, Thomas G. Lane.
  * Modified 2002-2009 by Guido Vollbeding.
- * Copyright (C) 2009-2010, D. R. Commander.
+ * Copyright (C) 2009-2011, D. R. Commander.
  * This file is part of the Independent JPEG Group's software.
  * For conditions of distribution and use, see the accompanying README file.
  *
@@ -215,12 +215,13 @@
 /* Known color spaces. */
 
 #define JCS_EXTENSIONS 1
+#define JCS_ALPHA_EXTENSIONS 1
 
 typedef enum {
 	JCS_UNKNOWN,		/* error/unspecified */
 	JCS_GRAYSCALE,		/* monochrome */
 	JCS_RGB,		/* red/green/blue as specified by the RGB_RED, RGB_GREEN,
-                 RGB_BLUE, and RGB_PIXELSIZE macros */
+				   RGB_BLUE, and RGB_PIXELSIZE macros */
 	JCS_YCbCr,		/* Y/Cb/Cr (also known as YUV) */
 	JCS_CMYK,		/* C/M/Y/K */
 	JCS_YCCK,		/* Y/Cb/Cr/K */
@@ -229,7 +230,18 @@
 	JCS_EXT_BGR,		/* blue/green/red */
 	JCS_EXT_BGRX,		/* blue/green/red/x */
 	JCS_EXT_XBGR,		/* x/blue/green/red */
-	JCS_EXT_XRGB		/* x/red/green/blue */
+	JCS_EXT_XRGB,		/* x/red/green/blue */
+	/* When out_color_space it set to JCS_EXT_RGBX, JCS_EXT_BGRX,
+	   JCS_EXT_XBGR, or JCS_EXT_XRGB during decompression, the X byte is
+	   undefined, and in order to ensure the best performance,
+	   libjpeg-turbo can set that byte to whatever value it wishes.  Use
+	   the following colorspace constants to ensure that the X byte is set
+	   to 0xFF, so that it can be interpreted as an opaque alpha
+	   channel. */
+	JCS_EXT_RGBA,		/* red/green/blue/alpha */
+	JCS_EXT_BGRA,		/* blue/green/red/alpha */
+	JCS_EXT_ABGR,		/* alpha/blue/green/red */
+	JCS_EXT_ARGB		/* alpha/red/green/blue */
 } J_COLOR_SPACE;
 
 /* DCT/IDCT algorithm options. */