Updated backward-cpp to v1.6 Hash: 701bcf38c9f3c4877e1b4a8651b9ce922b…

[hansonry]

…15969e

Building Open Clonk was failing for me because of some API changes with BFD used by backward-cpp. Looks like the version in openclonk was 6 years old the latest release of backward-cpp was 2 years old. So I picked that version. It looks like the new version of backward-cpp does some checking for backwards compatibility with BFD:

#ifdef bfd_get_section_flags
    if ((bfd_get_section_flags(fobj->handle.get(), section) & SEC_ALLOC) == 0)
#else
    if ((bfd_section_flags(section) & SEC_ALLOC) == 0)
#endif

I have not attempted to build this with the old version of BFD, so I don't know that the backward compatibility works. I was kinda hoping someone else could give it a test. I don't know anything about BFD or how I would install an older version on my system.

P.S. I also added VIM temp files to the .gitingore file.