Clarify comment.

I thought 'this' was referring to l->pattern->part[i].type.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

stats.c

@@ -495,7 +495,7 @@ static void find_literal_numbers(struct file *info)
 				}
 			}
 
-			/* We overload this as a flag to say we found mismatch */
+			/* first is cleared iff we found a mismatch.  */
 			if (first)
 				l->pattern->part[i].type = LITERAL;
 		}