This will be needed when we add `DW_FORM_strx*` and `DW_FORM_addrx*`
support, which requires us to fetch `DW_AT_str_offsets_base` and
`DW_AT_addr_base` attributes from the parent compilation unit. This
can't be done as we read the values, because it would create infinite
recursion (as we might try to parse the compilation unit's
`DW_FORM_strx*` encoded name before we get to the attribute). Having
getters ensures that we will perform lookups if they are needed.
Previously, the LineProgram objects were short-lived, and only created
inside DebugInfo::prepare_lines() to create a vector of sorted LineInfo
data.
However, Dwarf::LineProgram also contains other useful data, such as
index-to-string mapping of source directories and filenames.
This commit makes each Dwarf::CompilationUnit own its
Dwarf::LineProgram.
DebugInfo::prepare_lines() then iterates over the compilation units to
prepare its sorted vector of lines.
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 *
