FreeBSD apparently changed the magic sysctl mib values for devstats.
--- FAIL: TestDisk_io_counters (0.00s)
disk_test.go:39: error no such file or directory
disk_test.go:42: ret is empty, map[]
This code uses an undocumented, but exported, go stdlib method to fetch
the sysctl by string instead of mib.
Package common wasn't used for public functions. Place it in an
internal directory to prevent other packages from using.
Remove the distributed references to "HOST_PROC" and "HOST_SYS"
consts and combine into a common function. This also helps so that
if a env var is defined with a trailing slash all will continue to
work as expected.
Fixes#100
Michael Schurter