dsputil: convert remaining op_pixels_func

Convert to diffptr_t the line_size parameters still int.

Remove all the warnings in dsputil.c
libopencore-amrnb: cosmetics: Group all encoder-related code together

CC: libav-stable@libav.org
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
libopencore-amr: Conditionally compile decoder and encoder bits

CC: libav-stable@libav.org
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
libopencore-amrwb: Make AMR-WB ifdeffery more precise

The library might provide an encoder in the future, so it's better to
check for the presence of the decoder rather than just the library.

CC: libav-stable@libav.org
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
build: The libopencore-amrnb encoder depends on audio_frame_queue

CC: libav-stable@libav.org
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>