DWARF: Fix debug_info references to the abbreviations section (#2997)

The previous code assumed that each compile unit had its own
abbreviation section, and they are all in order. That's normally how
LLVM emits things, but in #2992 there is a testcase in which linking
of object files with IR files somehow ends up with a different order.

The proper fix is to track the binary offsets of abbreviations in the
abbreviation section. That section is comprised of null-terminated
lists, which each CU has an offset to the beginning of. With those
offsets, we can match things properly.

Add a testcase that crashes without this, to prevent regressions.

Fixes #2992
Fixes #3007

0 files changed, 0 insertions, 0 deletions