[gardening] Fix recently introduced typo: "assocated" → "associated"

Author: practicalswift

lib/IRGen/IRGenModule.h

@@ -213,7 +213,7 @@ class IRGenModuleDispatcher {
   /// Emit field type records for nominal types for reflection purposes.
   void emitFieldTypeMetadataRecords();
 
-  /// Emit assocated type references for nominal types for reflection purposes.
+  /// Emit associated type references for nominal types for reflection purposes.
   void emitAssociatedTypeMetadataRecords();
 
   /// Emit everything which is reachable from already emitted IR.