xvmc.h used FF_API_* macros before, but they were removed in
1c63aed2, leaving the include
unused.

The ones in android_camera.c and mediacodec_wrapper.c have been
added due to a misunderstanding, fixed in
c0bce367 and
13b77af2.

The one in mediacodec.c seems to never have been used at all.
Signed-off-by: Martin Storsjö <martin@martin.st>