include/{opt,inst}: Add regex parameter to opt_add_arg() calls

include/{opt,inst}: Add regex parameter to opt_add_arg() calls

The opt and inst modules use opt_add_arg() to register command line
arguments with a callback, however they omit the newly-added regex
argument, causing the callbacks not to be called.
This commit fixes the order of arguments passed to opt_add_arg() so
that the command line arguments are registered correctly.