0.1.39

Unix fault handler: do not change CPU state

When the fault handler is invoked, the CPU state is the same as the
state when the interrupt was triggered. Therefore, it is not
necessary for the fault handler to set the state when returning the
current context; in fact, this causes a wrong state to be set when
a user thread generates a page fault that is resolved without
blocking, which may cause any subsequent exception generated by the
thread to be handled as if it was generated by the kernel.