gdb: add lzma support by default (#9247)
gdb: add lzma support by default (#9247)

This is required at least on RedHat/Fedora.

Many (most?) other people distribute gdb with this support enabled:
http://tomszilagyi.github.io/2018/03/Remote-gdb-with-stl-pp
https://bugzilla.redhat.com/show_bug.cgi?id=1596490
LLNL/spack,iulian787/spack,iulian787/spack,iulian787/spack,LLNL/spack,LLNL/spack,iulian787/spack,LLNL/spack,LLNL/spack,iulian787/spack