USE_PTHREAD_FOR_ITIMER patch now merged in GHC 8.8, 8.10 and master

[Viktor Dukhovni]

For the record, the proposed patch has been merged into all three
post-8.6 branches.

Ditto with the "sys/sysctl.h requires sys/types.h" patch, so at this
point I'm not aware of any outstanding FreeBSD-specific issues waiting
to be "upstreamed".

-- 
    Viktor.