gdb: Remove use of deprecated_interactive_hook

gdb: Remove use of deprecated_interactive_hook

The deprecated_interactive_hook is not used within GDB.  It is used in
gdbtk, however this patch removes that use:

  https://sourceware.org/ml/insight/2019-q2/msg00001.html

So I think there is no longer a reason to keep this hook around.

This patch removes it.  There should be no user visible changes after
this commit.

gdb/ChangeLog:

	* defs.h (deprecated_interactive_hook): Delete declaration.
	* interps.c (clear_interpreter_hooks): Remove use of
	deprecated_interactive_hook.
	* top.c (deprecated_interactive_hook): Delete definition.
	* utils.c (maybe_quit): Remove use of deprecated_interactive_hook.