Experiemental NEON implementation of tiling/untiling that adds
specialized NEON function for tiling 8, 16, 32 bit per element
4x4 tiles. To optimize memory read/write sizes, there are functions that
process multiple horizontically adjactent tiles as well. These
are automatically picked when the width is an appropriate multiple.

To make this work, Mesa needs to be compiled with CFLAGS -mfpu=neon,
otherwise a compile error will be thrown.

Signed-off-by: Wladimir J. van der Laan <laanwj@gmail.com>