This algorithm is both iterative and recursive, so allocating on every
recursion, or when iterating each child is extremely costly.
Instead allow the on stack DIE to be re-initialized so it can be reused.
In the current implementation, only DIE objects that are created via
DIE::for_each_child() will have parent offsets.
DIE objects that are created with CompilationUnit::get_die_at_offset()
do not currently store a parent offset.
We may improve this in the future, but this is enough for what we
currently need.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
