Do not write build info if there are no files to emit

src/compiler/builder.ts

@@ -251,6 +251,9 @@ namespace ts {
             state.seenAffectedFiles = createMap<true>();
         }
 
+        state.emittedBuildInfo = !state.changedFilesSet.size &&
+            !state.affectedFilesPendingEmit;
+
         return state;
     }