Out of all operating systems ever supported by Swift, only Ubuntu 14.04
had libstdc++ 4.8, and Swift has sunset support for Ubuntu 14.04 for a
while now.
These tests were relying on sourcekitd parsing as frontend instead of
using the driver. Update them now to avoid churn when we fix command
line argument parsing in sourcekit.
The changes from clang-importer-sdk to clang-importer-sdk-nosource -I %t
are because clang-importer-sdk implies using -enable-source-import.
Rather than hack them up to use -Xfrontend, it is cleaner to just stop
using source import at all for these tests. Incidentally, this improved
fidelity in a few places. When using the generated swift modules we
also need to pass a target triple to sourcekit, which exposed some tests
that had mac-specific data. This is a systemic issue for sourcekit
tests, but for now just make those few specific tests that we had
problems with run only on mac.
* A bunch of them require objc_interop because they import code containing
Objective-C.
* Many others fail on Ubuntu 14.04 because the C++ there doesn't have a
functional std::regex implementation which is required by the
`complete-test` tool.
It may be possible to adjust some of these tests in the future to not
need these extra requirements, but this is a straightforward way to
clean up Linux test results for now.
