During Package CMO, SIL cloning happens during which

SILOptions::EnableSerializePackage info is lost.

SILVerifier needs this info to determine whether resilience
can be bypassed for decls serialized in a resiliently
built module when Package CMO optimization enabled.

This PR adds SerializePackageEnabled bit to Module format
and uses that in SILVerifier.

Resolves rdar://126157356

lib/Serialization/ModuleFileSharedCore.h

@@ -391,6 +391,9 @@ private:
     /// Whether this module is built with -experimental-allow-non-resilient-access.
     unsigned AllowNonResilientAccess : 1;
 
+    /// Whether this module is built with -experimental-package-cmo.
+    unsigned SerializePackageEnabled : 1;
+
     // Explicitly pad out to the next word boundary.
     unsigned : 3;
   } Bits = {};