-enable-source-import doesn't play nice with debug info, and we want to be
able to run all tests with -g added. The last few tests that require
-enable-source-import could be built with --no-debug-info, or however we
end up spelling that.
rdar://problem/18140021 (most of it)
Swift SVN r22742
The driver option -i now requires an input file as argument, and any
options after the input file will be treated as arguments to the
interpretted file.
This also renames the frontend option to -interpret, since it is parsed
as a flag, unlike -i. We could support -interpret in the driver if we
wanted, which would allow us to use --, but wouldn't work with shebang
scripts. For now, it's frontend-only.
Swift SVN r19718
