Remove unneeded NULL check in amd64's trap_fatal()

[dim]

Summary

Clang 3.7.0 (trunk) gives this warning about amd64's trap_fatal():

sys/amd64/amd64/trap.c:846:42: error: address of array '(__curthread())->td_name' will always evaluate to 'true' [-Werror,-Wpointer-bool-conversion]
                    (u_long)curproc->p_pid, curthread->td_name ?
                                            ~~~~~~~~~~~^~~~~~~ ~

Since td_name is an array member of struct thread, it can never be NULL,
so the check can be removed.

Note that I'm assuming curthread itself will never be NULL at this
point. If that is a possibility, the check could be changed into:

curthread ? curthread->td_name : ""

or something similar.

Test Plan

Build, boot, and possibly trigger a trap_fatal() on purpose.

[kib]

This looks fine.

While you are changing the printf(), you may as well remove the cast of p_pid to u_long, and 'l' format modifier. The pid_t is int32_t on all arches, and amd64 definitely does not need the cast.

Also, I do not believe that we can get curproc == NULL.

[dim]

Ah yes, curproc is defined as:

#define curproc         (curthread->td_proc)

so I removed the if statement, and folded the two printf() calls together.