* dwarf2-frame.c (struct dwarf2_cie): Add ptr_size member.

	Throughout, call read_encoded_value with ptr_size rather than addr_size.
	(decode_frame_entry_1): Remove redundant setting of
	addr_size.  Call gdbarch_dwarf2_addr_size rather than gdbarch_ptr_bit
	to determine addr_size in Dwarf versions < 4.  Set ptr_size dependent
	on examined frame section.  Add comment to explain why.
	* gdbarch.sh (dwarf2_addr_size): Define as variable.  Add lengthy
	comment to explain usage.
	* gdbarch.c: Regenerate.
	* gdbarch.h: Regenerate.

	* xstormy16-tdep.c (xstormy16_gdbarch_init): Set dwarf2_addr_size to 4.