X11 drag-and-drop corrections

X11 drag-and-drop corrections

* lisp/x-dnd.el (x-dnd-handle-drag-n-drop-event): Take cdddr of
client-message, skipping the selection information.
(x-dnd-do-direct-save): Do not erase the local copy of a remote
file if it was not in fact copied on behalf of the recipient.
(x-dnd-handle-xds-drop): Return proper action.

* src/xterm.c (x_term_init): Remove unused variable on non-GTK
builds.

(cherry picked from commit fa4260594fd2aae1c7d3e829b3cb15e344bc25ff)