[gdb/testsuite] Fix $eol regexp usage in some test-cases

[gdb/testsuite] Fix $eol regexp usage in some test-cases

Commit cff71358132 ("gdb/testsuite: tighten up some end-of-line patterns") replaced:
...
set eol "\[\r\n\]+"
...
with the more strict:
...
set eol "\r\n"
...
in a few test-cases, but didn't update all uses of eol accordingly.

Fix this in three gdb.ada test-cases.

Tested on x86_64-linux.

Approved-By: Andrew Burgess <aburgess@redhat.com>