Remote mirror build presets 27085666 (#3393)
* Only migrate the last swift-sdks setting when cascading build presets
Looping over these can cause CMake errors if a later preset tries
to override swift-sdks.
rdar://problem/27085666
* Break SwiftRemoteMirror into its own target.
We want to be able to build a target with just the platform-specific
libswiftRemoteMirror library. This should be a change in build logic
for existing presets but allows for a separate preset to be defined
that just builds the library if/when it's necessary.
- Add --build-swift-remote-mirror option to build-script-impl
- Add swift-remote-mirror known install component.
- Only add SwiftRemoteMirror targets if SWIFT_BUILD_REMOTE_MIRROR is on.
- Move libswiftRemoteMirror into the swift-remote-mirror install component.
- Add swift-remote-mirror install components to existing presets.
rdar://problem/27085666
* Add Remote Mirror build presets
This allows us to build just the OS-specific presets for integration
and testing.
rdar://problem/27085666
* Fix typo in Remote Mirror build preset
