opengl: add planar >=10bits support on Android:

Via GL_HALF_FLOAT, should work starting GLES 3.0.

Semiplanar is not supported as a CPU pass may be necessary to convert to
HALF_FLOAT:

Indeed, half-float data format consists of 1 sign bit, 5 exponent bits
and 10 mantissa bits. If you try to treat P010’s integer layout as
half-float, the GPU misinterprets those bits as exponent and mantissa,
causing corruption.