Add recursion detection to signal-safe backtrace

This cleans up the formatting of the backtrace considerably,
dodging the fact that a backtrace with recursion normally
emits hundreds of lines. Instead, simply write repeated symbols,
and add how many times the recursion occurred.
Also, it makes it look more like the "normal" backtrace.

Some fine details in the code are important for reducing
the amount of possible panic branches.

0 files changed, 0 insertions, 0 deletions