fix warn_extra_trailings.mk

use warnNoPrefix instead of fmt.Printf for warning message.
diff --git a/parser.go b/parser.go
index 059688f..bd10185 100644
--- a/parser.go
+++ b/parser.go
@@ -437,7 +437,7 @@
 		return
 	}
 	p.numIfNest = 0
-	warnNoPrefix(p.srcpos(), "extraneous text after `else` directive")
+	warnNoPrefix(p.srcpos(), "extraneous text after `else' directive")
 	return
 }
 
@@ -461,6 +461,9 @@
 			}
 		}
 	}
+	if len(trimSpaceBytes(data)) > 0 {
+		warnNoPrefix(p.srcpos(), "extraneous text after `endif' directive")
+	}
 	return
 }