gdb/

gdb/
	* eval.c (evaluate_subexp_standard) <OP_THIS>: Update the value_of_this
	caller to value_of_this.
	* p-exp.y: Update the value_of_this caller to value_of_this_silent.
	Twice.
	* valops.c (value_of_this): Remove parameter complain and variable ret.
	Update function comment.  Never return NULL by this code.
	(value_of_this_silent): New function.
	* value.h (value_of_this): Remove parameter complain.
	(value_of_this_silent): New declaration.