build: install CoreFoundation libraries for static builds

The static builds have dependencies on CoreFoundation which need to be
resolved when linking (not all platforms provide relocatable linking).
Install the CoreFoundation libraries during static builds.

Author: compnerd

CMakeLists.txt

@@ -60,8 +60,12 @@ if(ENABLE_TESTING)
   add_subdirectory(TestFoundation)
 endif()
 
-add_subdirectory(cmake/modules)
-
+if(NOT BUILD_SHARED_LIBS)
+  set_property(GLOBAL APPEND PROPERTY Foundation_EXPORTS
+    CoreFoundation CFXMLInterface CFURLSessionInterface)
+  install(TARGETS CoreFoundation CXFXMLInterface CFURLSessionInterface
+    DESTINATION lib/swift_static/$<LOWER_CASE:${CMAKE_SYSTEM_NAME}>)
+endif()
 # TODO(compnerd) install as a Framework as that is how swift actually is built
 install(DIRECTORY
           ${CMAKE_CURRENT_BINARY_DIR}/CoreFoundation.framework/Headers/
@@ -90,3 +94,5 @@ install(FILES
           CoreFoundation/Parsing.subproj/module.map
         DESTINATION
           lib/swift/CFXMLInterface)
+
+add_subdirectory(cmake/modules)