gdb/
	Code cleanup - constify struct lval_funcs.
	* dwarf2loc.c (pieced_value_funcs): Make it const.
	* infrun.c (siginfo_value_funcs): Likewise.
	* opencl-lang.c (opencl_value_funcs): Likewise.
	* valops.c (value_assign, value_ind): Make the funcs variable const.
	* value.c (struct value): Make location.computed.funcs target const.
	Rearrange the comments.
	(allocate_computed_value): Make the funcs parameter target const.
	(value_computed_funcs): Return the funcs target const.
	(value_free, value_copy, set_value_component_location): Make the funcs
	variable const.
	* value.h (allocate_computed_value): Make the funcs parameter target
	const.
	(value_computed_funcs): Return the funcs target const.
	* windows-tdep.c (tlb_value_funcs): Make it const.