ProcessInstanceInfoMatch: Don't match processes with no name if a name match was requested, take 2

Summary:
The previous attempt at making nameless process not match when searching for a
given name failed because the macos implementation was depending on this detail
in its partial matching strategy. Doing partial matching to avoid expensive
lookups is a perfectly valid thing to do, the way it was implemented seems
somewhat unexpected.

This patch implements it differently by providing special
methods in the ProcessInstanceInfoMatch which match only a subset of fields,
and changes mac host code to use those instead.

Then, it re-applies r373925 to get make the ProcessInstanceInfoMatch with a
name *not* match a nameless process.

Reviewers: JDevlieghere, teemperor, jingham

Subscribers: wallace, lldb-commits

Differential Revision: https://reviews.llvm.org/D68631

llvm-svn: 374529