Avoid ./ in zoneinfo entries in METALOG

Use of "find ." resulted in METALOG entries with an extra ./ -- e.g.,
./usr/share/zoneinfo/./America/Toronto. Avoid this by using globbing
via "find *" instead.

Reviewed by: brooks
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D719