backtrace functions in uClibc

[Carmelo AMOROSO]

Hi All,
I had a request from a customer to add support for backtrace functions
in uclibc. The current implementation available in glibc is based on
unwind functions provided by libgcc_s.so that is dlopen-ed for
traversing the stack frames and print them (using dwarf2 information).

glibc includes the __libc_dlopen function inside the C lib, while in
uClibc this is only available in libdl, and obviously we cannot have
libc depending on libdl.

I was thinking to add a libbacktrace.so into uClibc to provide this
functionality that can link libdl to use dlopen/dlsym, and I was
thinking to contribute this back if acceptable by the uclibc guys, so
your comments are welcome.

I'll include it on ST uclibc branch anyway as customer needs it, but I'd
prefer to work on something more widely useful.

Thanks,
Carmelo