[selftests] Fix selftest_fault_res_short() for clang
[selftests] Fix selftest_fault_res_short() for clang

The code in faulting_code2() trying to access address 0 was considered by
clang undefined behavior and, therefore, did not cause a page-fault as
expected by the test. The problem has been fixed by using bzero() which is
written in assembly.

vvaltchev/experimentOs,vvaltchev/experimentOs,vvaltchev/experimentOs,vvaltchev/experimentOs