Remove objfile argument from add_dyn_prop
    
    The objfile argument to add_dyn_prop is redundant, so this patch
    removes it.
    
    2018-01-17  Tom Tromey  <tom@tromey.com>
    
    	* gdbtypes.h (add_dyn_prop): Remove objfile parameter.
    	* gdbtypes.c (add_dyn_prop): Remove objfile parameter.
    	(create_array_type_with_stride): Update.
    	* dwarf2read.c (set_die_type): Update.