GCC 8.4 and Clang 13.0.1:
`cc1: note: unrecognized command-line option ‘-Wno-deprecated-non-prototype’ may have been intended to silence earlier diagnostics`
Addendum to commit 4e3bf252d
mkisofs and its components uses K&R-style function definitions
to support very old compilers. Modern compilers consider K&R syntax
to be deprecated. Clang therefore emits a large number of warnings
over this.