5.5.58  Count the number of cores available on host

This does not appear to be well standardized at present. The best Mythryl-level solution currently appears to be to do

    core_count =  posixlib::sysconf  "NPROCESSORS_ONLN";

(The complete list of values available via sysconf on your system may be found in src/c/lib/posix-process-environment/ml_sysconf.h which is synthesized at build time by src/c/config/ from (typically) /usr/include/unistd.h.)

Comments and suggestions to: