[Serialization] Add -swift-compiler-version option to swiftmodules

lib/Serialization/ModuleFileSharedCore.h

@@ -103,6 +103,12 @@ class ModuleFileSharedCore {
   /// Name to use in public facing diagnostics and documentation.
   StringRef PublicModuleName;
 
+  /// The version of the Swift compiler used to produce swiftinterface
+  /// this module is based on or build the module itself. This is
+  /// the most precise version possible - a compiler tag or version
+  /// if this is a development compiler.
+  llvm::VersionTuple SwiftCompilerVersion;
+
   /// \c true if this module has incremental dependency information.
   bool HasIncrementalInfo = false;