Require bindat and json.

Require bindat and json.
(gdb-jsonify-buffer, gdb-json-read-buffer)
(gdb-json-partial-output): JSON parsers copied from trunk.
(gdb-init-2): Enable GDB to pretty print STL containers, if possible.
(gdb-var-create-regexp, gdb-var-list-children-regexp-1)
(gdb-var-update-regexp-1): Delete.
(gdb-var-create-handler, gdb-var-list-children-handler-1)
(gdb-var-update-handler-1): Use json parsing as on trunk.  Parse
output of dynamic variable objects (STL containers).
(gdb-var-delete-1): Pass var1 as an explicit second argument.