bug(ptx): when -w is a large number then panics

[HackingRepo]

Hi, uutils mainteners

ptx panics when the -w option is a large number instead of erroing out like the GNU ptx

to reproduce that, i used

relunsec@relunsec:~/software/coreutils/target/debug$ ./ptx -w 99999999999 a
memory allocation of 49999999999 bytes failed
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Aborted                    (core dumped) ./ptx -w 99999999999 a
relunsec@relunsec:~/software/coreutils/target/debug$ 

then i compared it with GNU ptx as i see no panic when -2 is a large number