Linux 6.6 compat: fix configure error with clang (#15558)

With Linux v6.6.x and clang 16, a configure step fails on a warning that
later results in an error while building, due to 'ts' being
uninitialized. Add a trivial initialization to silence the warning.

Signed-off-by: Jaron Kent-Dobias <jaron@kent-dobias.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>