Merge pull request #22133 from Rostepher/fix-overlay-builds

[Build System: CMake] Correctly set the Darwin deployment targets when building the overlay projects

Author: Rostepher

cmake/modules/StandaloneOverlay.cmake

@@ -61,7 +61,7 @@ precondition(TOOLCHAIN_DIR)
 
 # Some overlays include the runtime's headers,
 # and some of those headers are generated at build time.
-add_subdirectory("${SWIFT_SOURCE_DIR}/include" "swift/include")
+add_subdirectory("${SWIFT_SOURCE_DIR}/include" "${SWIFT_SOURCE_DIR}/include")
 add_subdirectory("${SWIFT_SOURCE_DIR}/apinotes" "swift/apinotes")
 
 # Without this line, installing components is broken. This needs refactoring.