Use RAII idiom

(cherry picked from commit 15c0b5b356aad0c3032b96ed6db0ec70cbf719d3)

# Conflicts:
#	cores/esp8266/core_esp8266_wiring_digital.cpp

Author: dok-net

cores/esp8266/core_esp8266_wiring_digital.cpp

@@ -26,6 +26,7 @@
 #include "ets_sys.h"
 #include "user_interface.h"
 #include "core_esp8266_waveform.h"
+#include "interrupts.h"
 
 extern "C" {
 
@@ -147,7 +148,7 @@ void ICACHE_RAM_ATTR interrupt_handler(void*)
          (handler->mode & 1) == !!(levels & (1 << i)))) {
           // to make ISR compatible to Arduino AVR model where interrupts are disabled
           // we disable them before we call the client ISR
-          uint32_t savedPS = xt_rsil(15); // stop other interrupts
+          esp8266::InterruptLock irqLock; // stop other interrupts
           if (handler->functional)
           {
               ArgStructure* localArg = (ArgStructure*)handler->arg;
@@ -166,7 +167,6 @@ void ICACHE_RAM_ATTR interrupt_handler(void*)
           {
               handler->fn();
           }
-          xt_wsr_ps(savedPS);
       }
   }
   ETS_GPIO_INTR_ENABLE();