Remove unused variables.

Remove unused variables.

* gdbtk/generic/gdbtk-bp.c (gdb_get_breakpoint_info): remove new_obj.
  (gdb_set_bp): remove e.
* gdbtk/generic/gdbtk-cmds.c (gdb_listfiles): remove psymtab and pathname.
* gdbtk/generic/gdbtk-register.c (get_register): remove addr, lval and dummy.
  (setup_architecture_data): remove numregs.
  (gdb_reggrouplist): remove i.
* gdbtk/generic/gdbtk-varobj.c (variable_update): remove i.
  (variable_value): remove e.
  (variable_print): remove except.