gallium: fix ddebug on windows

By including the proper headers for getpid and for mkdir.

Fixes: 6ff0c6f4
       ("gallium: move ddebug, noop, rbug, trace to auxiliary to improve build times")
Signed-off-by: Dylan Baker <dylan.c.baker@intel.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
(cherry picked from commit 2877b655)