Fix the compilation warning below:
hydra-smtp-enum.c: In function ‘service_smtp_enum’:
hydra-mod.h:72:22: warning: statement will never be executed [-Wswitch-unreachable]
#define hydra_report fprintf
hydra-smtp-enum.c:220:11: note: in expansion of macro ‘hydra_report’
hydra_report(stdout, "[VERBOSE] ");
^~~~~~~~~~~~