(gud-gdb-massage-args, gud-sdb-massage-args)

(gud-gdb-massage-args, gud-sdb-massage-args)
(gud-pdb-massage-args): Delete.
(gdb, sdb, pdb): Don't pass gud-*-massage-args any more.
(gud-gdb-command-name): New var.  Put "--fullname" in there.
(gud-query-cmdline): Use the most recent executable as the default.
Don't add "--fullname" (it's only valid/meaningful for GDB).
(gud-xdb-marker-filter): Use match-string.
(gud-perldb-massage-args): Don't add "-d".
(gud-perldb-command-name): Add "-d".
(gud-common-init): If `massage-args' is nil, don't call it.
(gud-format-command): Don't hardcode point-min==1.