Upgrade from 3.2.7 to 3.2.8.

<ChangeLog>

Upgrade urgency CRITICAL: This release reverts back the Jemalloc upgrade

that is believed to potentially cause a server
deadlock. A MIGRATE crash is also fixed.

Two important bug fixes, the first of one is critical:

1. Apparently Jemalloc 4.4.0 may contain a deadlock under particular conditions. See https://github.com/antirez/redis/issues/3799. We reverted back to the previously used Jemalloc versions and plan to upgrade Jemalloc again after having more info about the cause of the bug.

2. MIGRATE could crash the server after a socket error. See for reference: https://github.com/antirez/redis/issues/3796.

</ChangeLog>