fileset: use set instead of list to mark predicates for efficiency (API)...
fileset: use set instead of list to mark predicates for efficiency (API)
This reduces cost of examining whether given predicate calls
'matchctx.status()' or 'matchctx.existing()' in 'getfileset()' at
runtime.
This kind of examination is used also in subsequent patch, which
detects unintentional 'matchctx.existing()' invocation per each
predicate evaluation.