[PATCH] Update PR ld/21562 tests for underscore targets

[Nick Clifton]

Hi H.J.

> 	* testsuite/ld-elf/pr21562c.t: Also provide ___start_scnfoo and
> 	___stop_scnfoo.
> 	* testsuite/ld-elf/pr21562d.t: Likewise.

Approved - please apply.

Cheers
  Nick