lib-storage: pop3c - fix invalid blank password check
lib-storage: pop3c - fix invalid blank password check

The pointer will never be NULL, as it's initialised pointing to an empty
string, and can only be overridden by setting it to another string. So
the test always failed. Instead, check the 1st character of the password.

LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot