libdwarf-code release 0.12.0

[davea42]

Adding the ability to use mmap instead of malloc for reading object section data.
Whether this improves library runtimes when reading gigabyte-plus object sections
is as yet unclear. It does not have significant impact on medium or smaller object
reading.

Improved the accuracy of dwarfdump's -k checking options with a much better
heuristic to get addresses from object data. Eliminates false error reports.

Checks for duplicate attributes in dwarf (generating an error) while
allowing callers to suppress the check.

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This discussion was created from the release libdwarf-code release 0.12.0.