Avoid re-check of usermode condition.

[kib]

Summary

This change should not change anything in the behavior of trap_pfault(), while eliminating obfuscation of jumping to the code which checks for reversed condition.

[kib]

Fix amd64 portion of the patch.

[alc]

sys/amd64/amd64/trap.c

662

The unconditional initialization of the variable "rv" to zero is now redundant. Arguably, zero was never a value of the correct type for its initialization, because it's not a KERN_*.

[kib]

Remove initialization of rv.