about deprecated function use and deprecated structure access unless the
user defines PNG_PEDANTIC_WARNINGS.  Added "#define PNG_NO_PEDANTIC_WARNINGS"
in the libpng source files.  Removed "-DPNG_CONFIGURE_LIBPNG" from the
makefiles and projects since the warnings no longer depend on this.

ported from libpng-1.4.0

These are mostly just cosmetic changes.