Bump eggdrop version to 1.8.2rc2

Summary:
Source files have been modified for the 1.8 branch,
version has now a dash before.

Test Plan: install-eggdrop

Reviewers: dereckson

Reviewed By: dereckson

Subscribers: Rashk0, tomjerr

Differential Revision: https://devcentral.nasqueron.org/D1178