libdw: set address size, offset size and version on fake CUs

There are three "fake CUs" that are associated with .debug_loc,
.debug_loclist and .debug_addr.  These fake CUs are used for "fake
attributes" to provide values that are stored in these sections
instead of in the .debug_info section. These fake CUs didn't have the
address size, offset size and DWARF version set. This meant that
values that depended on those properties might not be interpreted
correctly. One example was the value associated with a DW_OP_addrx
(which comes from the .debug_addr section).

Add a testcase using varlocs to test that addresses can correctly be
retrieved for gcc/clang, DWARF4/5 and 32/64 bits objects.

https://sourceware.org/bugzilla/show_bug.cgi?id=28220

Signed-off-by: Mark Wielaard <mark@klomp.org>
13 files changed