Fix incorrect comment in generator test

Author: jonas-schievink

src/test/ui/generator/resume-arg-size.rs

@@ -22,7 +22,7 @@ fn main() {
     };
 
     // Neither of these generators have the resume arg live across the `yield`, so they should be
-    // 4 Bytes in size (only storing the discriminant)
+    // 1 Byte in size (only storing the discriminant)
     assert_eq!(size_of_val(&gen_copy), 1);
     assert_eq!(size_of_val(&gen_move), 1);
 }