Have routines to report capture-file errors, using libwireshark error
codes and strings, that call through a pointer, so they can pop up
dialogs in GUI apps, print a message to the standard error on
command-line apps, and possibly do something different on server
programs.

Have init_report_message() take a pointer to structure containing those
function pointers, rather than the function pointers themselves, as
arguments.

Make other API changes to make that work.