Adds new sysctl type, bsdSysctlTypeStructTimeval to enable parsing of timevals from raw memory.
* Refactor meminfo_bsd.go to use sysctl_bsd.go * Fixed spelling.
* First pass of a sysctl_bsd source, exec_bsd + exec metrics * Incorportate PR feedback, including removing pre-build descriptions, unit conversion callback. * Remove redundant cached_description field, per PR feedback * Incorporate PR feedback