If you supply +ednsopt=nn[:xx] dighost.c accumulates the supplied
options in a global array, but doesn't dispose of old ones, eventually
triggering a fatal() error when the number reaches EDNSOPT_OPTIONS (100).

In batch mode this terminates the program.  In dig for iOS the fatal()
call doesn't happen, but the array fills up and a crash would occur.

The array of options is ultimately disposed of in destroy_libs(), but
it's unclear why the entries aren't cleaned up and the array
reinitialised for each query.