Bug#933299: isohybrid.pl should not be architecture dependent

[Timothy Pearson]

Package: syslinux-utils
Version: 3:6.04~git20190206.bf6db5b4+dfsg1-1

There are two versions of the hybrid ISO utility, a native C implementation and 
a Perl version.  Neither of these should be in the architecture-dependent 
(x86-only) syslinux-utils package, but especially the Perl version of the 
script should be moved to syslinux-common (which is architecture-independent).