[IA64] Fix trap #45 handling

In this case, the original author did not provide the related reason
string for die_if_kernel(), so the 'buf' is not initialized.

The original author wants to generic a 'SIGSEGV' and 'return', not want
to 'break' to fall to die.

[Probably irrelevent since we no longer support IA-32 execution. -Tony]

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>