Added preload instructions to armv6 encoder optimizations.
About 5% average speed-up on Tegra2 for VGA@30fps sequence.
Change-Id: I41d74737720fb71ce7a316f07555357822f3347e
Half pixel interpolations optimized in variance calculations. Separate
function calls to vp8_filter_block2d_bil_x_pass_armv6 are avoided.On
average, performance improvement is 6-7% for VGA@30fps sequences.
Change-Id: Idb5f118a9d51548e824719d2cfe5be0fa6996628