sim: cris: stop testing a.out explicitly [ld/13900]

Since gcc dropped support for a.out starting with 4.4.0 in 2009, it's
been impossible to verify this code actually still works.  Since it
crashes in ld, and it uses a config option that no other tests uses
and we want to remove, drop the test to avoid all the trouble.

sim/testsuite/cris/c/helloaout.c

@@ -1,14 +0,0 @@
-/* Make sure we don't just assume ELF all over.  (We have to jump
-   through hoops to get runnable a.out out of the ELF setup, and
-   having problems with a.out and discontinous section arrangements
-   doesn't help.  Adjust as needed to get a.out which says "pass".  If
-   necessary, move to the asm subdir.  By design, it doesn't work with
-   CRIS v32.)
-
-NB: We'd rely on kfail, but that doesn't skip compilation, and that's where
-the crash in ld happens to break the testcase.
-#target: disabled-cris-*-elf
-#kfail: ld/13900 cris-*-elf
-#cc: ldflags=-Wl,-mcrisaout\ -sim\ -Ttext=0
-*/
-#include "hello.c"