swift234

[CodeCompletion] Identify known operators and force a fixed sort order

In the new code-completion code path, force any known operators to go
through a fixed sort order. To identify operators unambiguously, add a
new BuiltinOperator code-completion kind to handle non-decl operators
(!, ., ?., and =).

rdar://problem/25994246
rdar://problem/23440367