Get rid of fmemopen in codec_apng.
Get rid of fmemopen in codec_apng.

On windows it was emulated by creating temporary file (which was never deleted).
Drive-by: remove local defines.
libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl