make ets_intr_lock_stack uint16_t and behave like the original on over/underflow

The PS register is 15 bits, we should store the whole thing as xt_wsr_ps()
writes the whole thing.

Also if there is an underflow, we should make sure interrupts are enabled.
Same goes for overflow making sure interrupts are disabled, although this
is less important.

Author: ChocolateFrogsNuts

cores/esp8266/core_esp8266_main.cpp

@@ -64,8 +64,8 @@ static uint32_t s_micros_at_task_start;
  * Max nesting seen by SDK so far is 2.
  */
 #define ETS_INTR_LOCK_NEST_MAX 7
-byte ets_intr_lock_stack[ETS_INTR_LOCK_NEST_MAX];
-byte ets_intr_lock_stack_ptr=0;
+uint16_t ets_intr_lock_stack[ETS_INTR_LOCK_NEST_MAX];
+byte     ets_intr_lock_stack_ptr=0;
 
 
 extern "C" {
@@ -131,11 +131,15 @@ extern "C" void optimistic_yield(uint32_t interval_us) {
 extern "C" void ets_intr_lock_nest() {
   if (ets_intr_lock_stack_ptr < ETS_INTR_LOCK_NEST_MAX)
      ets_intr_lock_stack[ets_intr_lock_stack_ptr++] = xt_rsil(3);
+  else
+     xt_rsil(3);
 }
 
 extern "C" void ets_intr_unlock_nest() {
   if (ets_intr_lock_stack_ptr > 0)
      xt_wsr_ps(ets_intr_lock_stack[--ets_intr_lock_stack_ptr]);
+  else
+     xt_rsil(0);
 }