* emacs.c (Finvocation_name): New function.

* emacs.c (Finvocation_name): New function.
	(Vinvocation_name): New variable.
	(init_cmdargs): Set it.
	(syms_of_emacs): defsubr Finvocation_name, staticpro and
	initialize Vinvocation_name.
	* lisp.h (Vinvocation_name): New extern declaration.
	* xterm.c (invocation_name): Variable deleted; use
	Vinvocation_name now.
	(x_text_icon, x_term_init): Use Vinvocation_name now instead of
	invocation_name.
	(x_term_init): Don't initialize invocation_name.
	(syms_of_xterm): Don't initialize or staticpro invocation_name.
	* xfns.c (invocation_name): Remove extern declaration for this.
	[HAVE_X11] (Fx_get_resource): Use Vinvocation_name now instead of
	invocation_name.
	[not HAVE_X11] (Fx_get_default): Same.