Restore use of #include

The change made in #663 were overwritten by #709. This change restores the switch from `#import` to `#include`.

The reason for this change is: Clang's MSVC compatibility does not handle `#import` statements outside of of objc.

> #import of type library is an unsupported Microsoft feature

Author: kastiglione

CoreFoundation/Base.subproj/ForFoundationOnly.h

@@ -63,7 +63,7 @@ CF_IMPLICIT_BRIDGING_DISABLED
 #endif
 
 #if (INCLUDE_OBJC || DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_WINDOWS) && !DEPLOYMENT_RUNTIME_SWIFT
-#import <objc/message.h>
+#include <objc/message.h>
 #endif
 
 // ---- CFBundle material ----------------------------------------