The wrapper_core_bt_on_error.sh should get a backtrace if a coredump appears. This didn't work because the execfn could not be extracted via file for asterisk (it works with other programs):
$ file core core: ELF 64-bit LSB core file, x86-64, version 1 (SYSV), too many program headers (2201)
Add a fallback execfn path so it works in this case too.
