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
... in the experimental code-completion path. They seem to be generally
useful as a baseline result still as long as they are guaranteed to be
the first result.
rdar://problem/25177968
The code goes into its own sub-tree under 'tools' but tests go under 'test',
so that running 'check-swift' will also run all the SourceKit tests.
SourceKit is disabled on non-darwin platforms.
