We want to report the tor version, even on platforms that don't have
backtrace support (like Android).

This commit stores the backtrace Tor version, regardless of USE_BACKTRACE.

Preparation for 31571.

Previously, we just logged it in the crash handler.

Part of 31571.

Part of 31571.

…ation

Some platforms (macOS, maybe others?) can swallow the last write before an
abort. This issue is probably caused by a race condition between write
buffer cache flushing, and process termination. So we write an extra
newline, to make sure that the message always gets through.

Fixes bug 31571; bugfix on 0.3.5.1-alpha.

We can't use strlcat() or strlcpy() in torerr, because they are defined
in string/compat_string.h on some platforms, and string uses torerr.

Part of 31571.