Use case: You're working with a debug version of Qt Creator and you're
interested in getting a backtrace displayed as soon as Qt Creator
crashes without searching for the core file, starting your debugger, ...

Once a 'serious signal' (currently SIGILL, SIGFPE, SIGSEGV, SIGBUS,
SIGPIPE) is delivered, a popup displays the following debug information:

 - Qt Creator version (same as in the about dialog)
 - Kernel version (uname -a)
 - GNU/Linux Distribution (/etc/lsb-release)
 - Backtrace (by gdb)

Please note that this crash handler is built and used only in debug mode
on GNU/Linux. It's solely meant as a convenience tool for the developer.

In contrast to the breakpad integration, this crash handler operates
'offline'. There is no network i/o involved.

Change-Id: Idcfb1bf1ad68942615ecfe0dffc0d03154455049
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>
Reviewed-by: hjk <qthjk@ovi.com>