SystemSan: use tgkill on precise pid (#8615)
SystemSan: use tgkill on precise pid (#8615)

This patch is meant for `tgkill` to use the right thread, so that we get
the right stack trace every time
google/oss-fuzz,google/oss-fuzz,google/oss-fuzz,google/oss-fuzz,google/oss-fuzz,google/oss-fuzz,google/oss-fuzz,google/oss-fuzz,google/oss-fuzz,google/oss-fuzz,google/oss-fuzz