drivers/dri/i965: add missing #include

brw_bufmgr.h uses time_t without include time.h, so the build fails under musl.

Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>

src/mesa/drivers/dri/i965/brw_bufmgr.h

@@ -37,6 +37,8 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
+#include <time.h>
+
 #include "util/u_atomic.h"
 #include "util/list.h"