runtests: consistently write the test check summary block

The memory check character was erroneously omitted if the memory
checking file was not available for some reason, making the block of
characters an inconsistent length.

tests/runtests.pl

@@ -1608,6 +1608,7 @@ sub singletest_check {
             my $cmdtype = $cmdhash{'type'} || "default";
             logmsg "\n** ALERT! memory tracking with no output file?\n"
                 if(!$cmdtype eq "perl");
+            $ok .= "-"; # problem with memory checking
         }
         else {
             my @memdata=`$memanalyze "$logdir/$MEMDUMP"`;