Bug 768928 Followup to compile harder with external linkage r=patrick brunschwig

mailnews/mime/cthandlers/pgpmime/nsPgpMimeProxy.cpp

@@ -22,6 +22,7 @@
 #include "nspr.h"
 #include "plstr.h"
 #include "nsIPgpMimeProxy.h"
+#include "nsComponentManagerUtils.h"
 
 static NS_DEFINE_CID(kMimeObjectClassAccessCID, NS_MIME_OBJECT_CLASS_ACCESS_CID);