(my_strtol): New function.

(my_strtol): New function.
(main): Use it instead of atoi to convert argument strings to
major and minor device numbers.  Now, mknod diagnoses invalid
device numbers and accepts octal and hexadecimal as well as
decimal string arguments.  Ralf Lammers
<rlammers@physik.uni-osnabrueck.de> suggested that mknod accept
hex device numbers for compatibility with HPUX's mknod program.