Attribute __real_system_restart_local() as (noreturn) (#7167)

* Attribute `__real_system_restart_local()` as `(noreturn)`
* As well as `abort()`.
* Aggragate two decls into `coredecls.h`.

Author: jjsuwa

Diff for: cores/esp8266/Esp.cpp

@@ -193,9 +193,6 @@ bool EspClass::rtcUserMemoryWrite(uint32_t offset, uint32_t *data, size_t size)
     }
 }
 
-
-
-extern "C" void __real_system_restart_local();
 void EspClass::reset(void)
 {
     __real_system_restart_local();

Diff for: cores/esp8266/core_esp8266_postmortem.cpp

@@ -32,11 +32,10 @@
 #include "pgmspace.h"
 #include "gdb_hooks.h"
 #include "StackThunk.h"
+#include "coredecls.h"
 
 extern "C" {
 
-extern void __real_system_restart_local();
-
 // These will be pointers to PROGMEM const strings
 static const char* s_panic_file = 0;
 static int s_panic_line = 0;

Diff for: cores/esp8266/coredecls.h

@@ -21,6 +21,7 @@ void esp_schedule();
 void tune_timeshift64 (uint64_t now_us);
 void disable_extra4k_at_link_time (void) __attribute__((noinline));
 bool sntp_set_timezone_in_seconds(int32_t timezone);
+void __real_system_restart_local() __attribute__((noreturn));
 
 uint32_t sqrt32 (uint32_t n);
 uint32_t crc32 (const void* data, size_t length, uint32_t crc = 0xffffffff);