gdb.ada/info_exc.exp: Adjust expected output in "info exception" test.

gdb.ada/info_exc.exp: Adjust expected output in "info exception" test.

Since multi_line was moved to gdb.exp in a slightly stricter form,
The gdb.ada/info_exc.exp:info exceptions test has been failing.
This is because it now expects a new-line sequence at the end of
each argument given to multi_line, including ".*". But the intent
when writing the test was to signify "could-be-nothing-at-all".
As a result, the test fails on x86_64-linux with a runtime built as
recommended, because of that
extra new-line sequence.

gdb/testsuite/ChangeLog:

        * gdb.ada/info_exc.exp: Adjust "info exceptions" expected output.