Update to latest version

[Kicer86]

New version has support for PE files.
I've already tried to build it on windows, but pecoff.c required dwarf.c to be included to project which requires dwarf.h which is not available on windows by default.

[Kicer86]

Please check my fork for details: https://github.com/Kicer86/libbacktrace

[RichardLangFromNZ]

FYI there is a currently active pull request bringing cmake support to the root https://github.com/ianlancetaylor/libbacktrace project