mesa: Remove prog_hash_table.c

mesa: Remove prog_hash_table.c

Here we make the prog_hash_table functionally equivalent to
the one in util by wrapping the remaing functions that differ.

We also move the functions to the header so we can remove the c
file.

This enables us to do a step-by-step replacement of the table.

Signed-off-by: Thomas Helland <thomashelland90@gmail.com>
Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>