Upgrade from 4.0-rc1 to 4.0-rc2.

<ChangeLog>

Upgrade urgency LOW: This release mainly fixes a rare GEO API bug and a crash

related to the modules subsystem.

Redis 4.0.0-RC2 (version number 3.9.102) just fixes two bugs:

1. GEORADIUS could fail reporting items with very big radius lengths because of a bug in the bounding box computation function. This was fixed and tests with large radius sizes were added.

2. There was a crash in the modules subsystem that was not merged into RC1 for an error, while it was already fixed into the "unstable" branch.

</ChangeLog>