swift234

[test] Added an integrated "-test-createCompilerInvocation" tool to swift-ide-test.

This is very basic: it just sees whether, given a set of driver arguments, the
swift::driver::createCompilerInvocation API returns a non-null
CompilerInvocation.

Unlike other modes of swift-ide-test, this mode requires that
"-test-createCompilerInvocation" be the first argument passed to swift-ide-test.
This is because it is handled separately from llvm::cl::ParseCommandLineOptions
so the remaining arguments can be passed through directly to
swift::driver::createCompilerInvocation without any interference from that
parser.

Additionally, added a test which uses this tool to try to create a
CompilerInvocation for a handful of basic driver commands.

Swift SVN r20973