with the help of "cppi".

when building on AIX.

otherwise AIX reserves "jmpbuf" and renames it to "__jmpbuf".

from png.h

to disable the warnings in pngconf.h

and added "#define PNG_NO_PEDANTIC_WARNINGS" in the libpng source files.

It will be replaced in the future with a function that accounts for gamma.

    longjmp function as well as returning a pointer to the setjmp
    jmp_buf buffer, and marked direct access to jmpbuf 'deprecated'.
    (John Bowler)