add stack_thunk_yield()

Author: mcspr

Diff for: cores/esp8266/StackThunk.cpp

@@ -150,4 +150,9 @@ void stack_thunk_fatal_smashing()
     __stack_chk_fail();
 }
 
+void stack_thunk_yield()
+{
+    optimistic_yield(10000);
+}
+
 }

Diff for: cores/esp8266/StackThunk.h

@@ -31,6 +31,8 @@
 extern "C" {
 #endif
 
+extern void stack_thunk_yield(void);
+
 extern void stack_thunk_add_ref();
 extern void stack_thunk_del_ref();
 extern void stack_thunk_repaint();