executor: don't create all threads when spot a root syscall
executor: don't create all threads when spot a root syscall

xairy/syzkaller,hyz0906/syzkaller,zoulasc/syzkaller,google/syzkaller,xairy/syzkaller,dotweiba/syzkaller,google/syzkaller,zoulasc/syzkaller,xairy/syzkaller,google/syzkaller,sploving/syzkaller,zoulasc/syzkaller,dotweiba/syzkaller,sploving/syzkaller,hyz0906/syzkaller,sploving/syzkaller,xairy/syzkaller,lorenzo-stoakes/syzkaller,sploving/syzkaller,xairy/syzkaller,xairy/syzkaller,lorenzo-stoakes/syzkaller,hyz0906/syzkaller,dotweiba/syzkaller,hyz0906/syzkaller,zoulasc/syzkaller,google/syzkaller,google/syzkaller,google/syzkaller,lorenzo-stoakes/syzkaller,google/syzkaller,dotweiba/syzkaller,xairy/syzkaller,hyz0906/syzkaller