Moved Swift's option table from swiftDriver into a new swiftOption library.

This allows swiftFrontend to drop its dependency on swiftDriver, and could
someday allow us to move the integrated frontend's option parsing out of
swiftFrontend (which would allow other tools which use swiftFrontend to
exclude the option table entirely).

Swift SVN r19824

include/swift/CMakeLists.txt

@@ -1 +1 @@
-add_subdirectory(Driver)
+add_subdirectory(Option)