(gdb-reset): Update speedbar if necessary.

(gdb-reset): Update speedbar if necessary.
(gdb-var-evaluate-expression-handler, gdb-var-update-handler):
Use a token for pending-triggers to ensure gdb-var-update
gets called once per user input again for pre-GDB 6.4.
(gdb-var-delete): Match on more complex expressions.
(gdb-var-list-children-handler, gdb-var-create-handler):
Use a token for consistency.