[serialization] Include the module name in the serialized AST data.

We don't currently use this for anything, but if we have the module name
available and easy to access in the bitstream, we can drop the wrapper
around the serialized AST that's put into the binary itself for use by LLDB.

Swift SVN r12919

lib/Serialization/ModuleFile.cpp

@@ -61,6 +61,10 @@ validateControlBlock(llvm::BitstreamCursor &cursor,
       result = ModuleStatus::Valid;
       break;
     }
+    case control_block::MODULE_NAME:
+      // Ignore the module name; this is only interesting when the serialized
+      // data is the only clue to which module this is.
+      break;
     default:
       // Unknown metadata record, possibly for use by a future version of the
       // module format.