avutil/crc: Dont limit CRC32 standard tables

Currently, standard tables like AV_CRC_32_IEEE and such are being generated (or
provided in case the user compiles with hardcoded tables) with only 257 elements.
We're missing a considerable boost in performance by not making them with a size
of 1024 elements instead.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
