vm/gvisor: fix current binary lookup
vm/gvisor: fix current binary lookup

os.Args[0] can be just binary name which was looked up using $PATH.
In such case copy will fail because the path does not exist.
Lookup binary name using $PATH.

google/syzkaller,xairy/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller