[Crash-utility] [PATCH] bug on get_be_long() and improvement of bt

Hi Dave, There is a bug on get_be_long() that causes high 32 bits truncated. As a result, we get wrong registers values from dump file. Patch 1 fixes this. Once we can get right cpu registers values, it's better to use the sp/ip for backtracing the active task. This can show a more accurate backtrace, not including those invalid frames beyond sp. pathes 2 and 3 do this on kvmdump case(virsh dump). To verify: run that km_probe.c test module on a x86_64 system, then `echo q > /proc/sysrq-trigger' to trigger the kprobe which does looping in post_handler. Then vrish dump then crash. -- Thanks, Hu Tao