Fixed import for Python 3.

Fixed the trivial import bug that prevented the Python 3 version of MPO
from running. On the way fixed the trivial C bug that prevented
Convert.c from compiling properly in a Mac OS X environment for a
Python 3 target.

PIL/JpegImagePlugin.py

@@ -699,7 +699,7 @@ def jpeg_factory(fp=None, filename=None):
     try:
         if mpheader[45057] > 1:
             # It's actually an MPO
-            from MpoImagePlugin import MpoImageFile
+            from .MpoImagePlugin import MpoImageFile
             im = MpoImageFile(fp, filename)
     except (TypeError, IndexError):
         # It is really a JPEG

libImaging/Convert.c

@@ -49,6 +49,10 @@
 #define L(rgb)\
     ((INT32) (rgb)[0]*299 + (INT32) (rgb)[1]*587 + (INT32) (rgb)[2]*114)
 
+#ifndef uint
+#define uint UINT32
+#endif
+
 /* ------------------- */
 /* 1 (bit) conversions */
 /* ------------------- */