signal: signal handler may cause task's state error

For example, task is blocked by nxsem_wait(sem1), use nxsem_wait(sem2)
in signal handler, and take sem2 successfully, after exit from signal
handler to task, nxsem_wait(sem1) returns OK, but the correct result
should be -EINTR.

Signed-off-by: Zeng Zhaoxiu <zhaoxiu.zeng@gmail.com>

arch/sim/src/sim/up_sigdeliver.c

@@ -66,13 +66,6 @@ void sim_sigdeliver(void)
   irqstate_t flags = enter_critical_section();
 #endif
 
-  /* Save the errno.  This must be preserved throughout the signal handling
-   * so that the user code final gets the correct errno value (probably
-   * EINTR).
-   */
-
-  int saved_errno = get_errno();
-
 #ifdef CONFIG_SMP
   /* In the SMP case, we must terminate the critical section while the signal
    * handler executes, but we also need to restore the irqcount when the
@@ -134,10 +127,6 @@ void sim_sigdeliver(void)
     }
 #endif
 
-  /* Restore the saved errno value */
-
-  set_errno(saved_errno);
-
   /* Allows next handler to be scheduled */
 
   rtcb->xcp.sigdeliver = NULL;