Redmine #5233: Fix uptime calculation on Solaris.

Also make it a little less verbose when detecting errors, since it
will retry using "uptime" command if the kstat probing is
unsuccessful.
Minor logging message fixes
00_basics/03_bodies/evaluation-should-respect-ifvarclass.cf: more ifvarclass cases
Evaluate ifvarclass and depends_on before other constraints

This short-circuits evaluation of other constraints in the promise iteration
if ifvarclass or depends_on excludes the promise. The benefit is primarily
that system functions with side-effects are not evaluated if the promise
should be excluded anyway.

Modify acceptance test from Ted to also test depends_on.

Close #5248