util: Move the open-addressing linear-probing hash_table to src/util.

util: Move the open-addressing linear-probing hash_table to src/util.

This hash table is used in core Mesa, the GLSL compiler, and the i965
driver, which makes it a good candidate for the new src/util module.

It's much faster than program/hash_table.[ch] (see commit 6991c2922f5
for data), and José's u_hash_table.c has a comment saying Gallium should
probably consider switching to a linear probing hash table at some point.
So this seems like the best candidate for a shared data structure.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
v2 (Jason Ekstrand): Pick up another hash_table use and patch up scons

Signed-off-by: Jason Ekstrand <jason.ekstrand@intel.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>