non-reg tests: support alternative location for lctl, lfs, lhsmd_posix...
Fix: s/creation/creation_time/
migration: fix skipped and error counters.

The skipped and errors counters were reinitialized for each loop
of the migration pass.
migration: suspend current migration if error count and error rate
are too high.

New migration parameters suspend_error_pct and suspend_error_min
to control this.
add migration policy and lru_sort_attr tests