libpng never returns the palette size when the palette pointer argument
is nullptr.
If it worked before, it's because paletteSize was uninitialized and luck.
This fixes the loading of vkbd images from kbd subfolder:
kbd/keys_s_c4.png
kbd/keys_s4.png
kbd/nums_s4.png
kbd/keys_c4.png
kbd/syms_s4.png
kbd/keys4.png
kbd/nums4.png
kbd/syms4.png
This tries to make our code a bit more compliant with our code formatting
conventions. For future use, this is the command I used:
git ls-files "*.cpp" "*.h" | xargs sed -i -e 's/[ \t]*$//'
Sometimes we can have an 8bit file for example that has a palette of 16 colors or less, so we need to go by the bit depth rather than inferring the bit depth from the palette size.
svn-id: r53917
