On macOS 10.13 (High Sierra), disksup cannot grab information
for any disks that use the new APFS file system. The reason
is that the invocation of /bin/df explicitly limits the
type of file systems to show:

    /bin/df -i -k -t ufs,hfs

Add 'apfs' to also look at disks with APFS:

    /bin/df -i -k -t ufs,hfs,apfs

That also works on older versions of macOS.

An alternative solution would be to use the -l flag to only
show local file systems. However, that would mean that USB
memory sticks would also show up, and it might not be desirable
to monitor them.

https://bugs.erlang.org/browse/ERL-461

Update compiler documentation and remove superfluous erlc flags.

* jrobhoward/os_mon/fix-freebsd_get_os_wordsize/PR-1039/OTP-13601:
  Fix memsup:get_os_wordsize() on 64-bit Linux PPC
  os_mon: Test wordsize of memsup:get_os_wordsize/0
  Fix memsup:get_os_wordsize() on 64-bit FreeBSD

* mururu/os_mon/cpu-sup-osx/PR-1049/OTP-13597:
  os_mon: Implement cpu_sup:util/0,1 on OSX

cpu_sup:util/0,1 works on OSX as well.