bug: icaltime_is_floating() declared but appears to have no implementation.

[Michael Cree]

The function icaltime_is_floating() is declared in libical/ical.h as

int icaltime_is_floating(const struct icaltimetype t);

however there appears to be no implementation of this function in
libical.  Indeed, when linking a module calling this function with
libical an undefined reference to icaltime_is_floating is reported.

Cheers
Michael.