swr: Prune empty nodes in CalculateProcessorTopology.

swr: Prune empty nodes in CalculateProcessorTopology.

CalculateProcessorTopology tries to figure out system topology by
parsing /proc/cpuinfo to determine the number of threads, cores, and
NUMA nodes.  There are some architectures where the "physical id" begins
with 1 rather than 0, which was creating and empty "0" node and causing a
crash in CreateThreadPool.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97102
Reviewed-By: George Kyriazis <george.kyriazis@intel.com>
CC: <mesa-stable@lists.freedesktop.org>