Fix checkfile

Author: som-snytt

tests/neg/t6124.check

@@ -42,11 +42,11 @@
 22 |  val x3 = 52_ // error
    |             ^
    |             trailing separator is not allowed
--- Error: tests/neg/t6124.scala:24:12 --------------------------------------------------------------------------------
+-- Error: tests/neg/t6124.scala:24:12 ----------------------------------------------------------------------------------
 24 |  val x5 = 0_x52 // error // error
    |            ^
    |            trailing separator is not allowed
--- Error: tests/neg/t6124.scala:24:11 --------------------------------------------------------------------------------
+-- Error: tests/neg/t6124.scala:24:11 ----------------------------------------------------------------------------------
 24 |  val x5 = 0_x52 // error // error
    |           ^
    |           Invalid literal number