[SPI] Serialize SPI attributes on imports

lib/Serialization/ModuleFormat.h

@@ -55,7 +55,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 541; // movable guaranteed scopes
+const uint16_t SWIFTMODULE_VERSION_MINOR = 542; // SPI
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///
@@ -797,18 +797,25 @@ namespace input_block {
     SEARCH_PATH,
     FILE_DEPENDENCY,
     DEPENDENCY_DIRECTORY,
-    MODULE_INTERFACE_PATH
+    MODULE_INTERFACE_PATH,
+    IMPORTED_MODULE_SPIS,
   };
 
   using ImportedModuleLayout = BCRecordLayout<
     IMPORTED_MODULE,
     ImportControlField, // import kind
     BCFixed<1>,         // scoped?
+    BCFixed<1>,         // has spis?
     BCBlob // module name, with submodule path pieces separated by \0s.
            // If the 'scoped' flag is set, the final path piece is an access
            // path within the module.
   >;
 
+  using ImportedModuleLayoutSPI = BCRecordLayout<
+    IMPORTED_MODULE_SPIS,
+    BCBlob // SPI names, separated by \0s
+  >;
+
   using LinkLibraryLayout = BCRecordLayout<
     LINK_LIBRARY,
     LibraryKindField, // kind