Fix QueryCounterBits for timestamp queries
Our timestamp queries are 36-bit in i965. We're doing that in iris too, but we don't advertise the GL_QUERY_COUNTER_BITS for timestamp queries properly, so apps can't properly use that to handle wraparound.
Dave has patches for this in his iris-timestamp-fixes branch that change PIPE_CAP_QUERY_TIMESTAMP from a boolean to an integer which is the number of bits. Then st can use that. We'd need to convert the other drivers, and update the documentation.
I also am not sure whether the 36-bit thing still makes any sense, given that our clocks are different these days...