rebuild-pysnmp-mibs is used to compile the original mib definitions into the format used by pysnmp.
pysnmp-mib-rebuild-dir must contain the old compiled mibs (i.e. IF-MIB.py). rebuild-pysnmp-mibs will then
try to find the original mib definitions and recompile them. By default rebuild-pysnmp-mibs searches in
/usr/local/share/snmp, /usr/local/share/mibs, /usr/share/snmp and /usr/share/mibs.
It is possible to specify another source directory with the -s mib-text-dir option. This directory will
then be searched instead.