Changeset 6d9d7b1 in rtems-libbsd for freebsd/sys/sys

Critical bug fix for callouts

FreeBSD has two callout executors, one in software and one in hardware
interrupt context. In libbsd, all callouts are executed by the timer
server. Entirely remove the different execution contexts for libbsd.
Previously, this was not properly done which could result an invalid
callout_drain() sequence leading to system memory corruption.