libdwarf -code release 2.0.0.

[davea42]

Fixed a longstanding bug in configure.ac
which began to cause builds to fail with recent
autoconf.

Fixed a problem in test/CmakeLists.txt that caused
current builds to fail on Msys2 Mingw64. Had been
working for many months.

Updated the error report (for zlib, zstd) when
decompression exceeds a heuristic. Now reports
the compressed-len and the uncompressed-len.

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This discussion was created from the release libdwarf -code release 2.0.0..