A parse-only option is needed for parse performance tracking and the current option also includes semantic analysis.
Most tests were using %swift or similar substitutions, which did not include the target triple and SDK. The driver was defaulting to the host OS. Thus, we could not run the tests when the standard library was not built for OS X. Swift SVN r24504
This reverts commit 2711ca86de7bf6a7885ccea24219a48a590b1e95. Swift SVN r23577
Swift SVN r23573
Swift SVN r16285