Log Message:
Update to 1.2.40:

version 1.2.40beta01 [August 20, 2009]
  Removed an extra png_debug() recently added to png_write_find_filter().
  Fixed incorrect #ifdef in pngset.c regarding unknown chunk support.

version 1.2.40rc01 [September 2, 2009]
  Various bugfixes and improvements to CMakeLists.txt (Philip Lowman)

version 1.2.40 and 1.0.49 [September 10, 2009]
  No changes.