Screen/OSX: Fix Screen('Computer') busfreq, cpufreq, usermem reporting.

sysctl() doesn’t report proper values for these properties but simply
makes shit up as 32 Bit values for “backwards compatibility” [quoting
Apple kernel docs]. WTF?!?
sysctlbyname() for the same properties otoh. reports proper values
inside 64-Bit integers. Apparently fixing both system calls going
forward was asked too much from the kernel engineers of the company
that pays insane amounts of attention to detail.

-> Fix this latest crap by Apple.
-> Screen for 64-Bit Octave and Matlab on OSX rebuilt and tested.