addr2line.c: fix `DW_FORM_ref_addr` parsing for DWARF 2 (#8146)

	addr2line.c: fix DW_FORM_ref_addr parsing for DWARF 2

	This fixes a crash when retrieving backtrace info with YJIT enabled on
	macOS with Rust 1.71.0. Since Rust 1.71.0, the DWARF info generated by
	the Rust compiler uses DW_FORM_ref_addr instead of DW_FORM_ref4 for
	pointers to other DIEs.
	DW_FORM_ref_addr representation in DWARF 2 is different from DWARF 3+,
	so we need to handle it separately.
	This patch fixes the parsing of DW_FORM_ref_addr for DWARF 2, which is
	the default DWARF version Rustc uses on macOS.

	See the DWARF 2.0.0 spec, section 7.5.4 Attribute Encodings
	https://dwarfstd.org/doc/dwarf-2.0.0.pdf

	https://bugs.ruby-lang.org/issues/19789
	---
	 addr2line.c | 40 ++++++++++++++++++++++++++--------------
	 1 file changed, 26 insertions(+), 14 deletions(-)