gdb/testsuite: fix default behavior of runto

The documented behavior of proc runto is to not emit a PASS when
succeeding to to run to the specified location, but emit a FAIL when
failing to do so.  I suppose the intent is that it won't pollute the
results normally passing tests (although I don't see why we would care),
but make visible any problems.

However, it seems like the implementation makes it default to never
print anything.  "no-message" is prependend to "args", so if "message"
is not passed, we will always take the   path that sets print_fail to 0,
which will silence any failure.

This unfortunately means that tests relying on runto_main won't emit a
FAIL if failing to run to main.  And since commit 4dfef5be
("gdb/testsuite: make runto_main not pass no-message to runto"), tests
don't emit a FAIL themselves when failing to run to main.  This means
that tests failing to run to main just fail silently, and that's bad.

This can be reproduced by hacking gdb.base/template.exp like so:

    diff --git a/gdb/testsuite/gdb.base/template.c b/gdb/testsuite/gdb.base/template.c
    index bcf39c377d92..052be5b79d73 100644
    --- a/gdb/testsuite/gdb.base/template.c
    +++ b/gdb/testsuite/gdb.base/template.c
    @@ -15,6 +15,14 @@
        You should have received a copy of the GNU General Public License
        along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

    +#include <stdlib.h>
    +
    +__attribute__((constructor))
    +static void c (void)
    +{
    +  exit (1);
    +}
    +
     int
     main (void)
     {

Running the modified gdb.base/template.exp shows that it exits without
printing any result.

Remove the line that prepends no-message to args, that should make
runto's behavior match its documentation.

This patch will appear to add many failures, but in reality they already
existed, they were just silenced.

Change-Id: I2a730d5bc72b6ef0698cd6aad962d9902aa7c3d6