[syslinux] mkdiskimage: perl error and lack of checks

[Gene Cumm]

Per http://forum.tinycorelinux.net/index.php/topic,14323.0.html I can confirm:

1) Specifying an MBR ID results in an error due to the lack of a "use"
statement.

2) Specifying a non-decimal value may result in $id being undefined.

I have a patch for the first however should #2 abort operation,
attempt to translate 4 ASCII bytes to an int or print a warning and
use a random value?  I'd lean against performing the third.

-- 
-Gene