LLVM unwinder, not compatible with glibc

 llvm-libunwind is the LLVM unwinder, with platform support for DWARF
 unwind info, SjLj, and ARM EHABI. Using it for packaging work inside
 Debian is not recommended, incompatible with glibc.
 .
 The low level libunwind API was designed to work either in-process (aka local)
 or to operate on another process (aka remote), but only the local path has
 been implemented. Remote unwinding remains as future work.