bpo-39882: Py_FatalError() logs the function name (GH-18819)

The Py_FatalError() function is replaced with a macro which logs
automatically the name of the current function, unless the
Py_LIMITED_API macro is defined.

Changes:

* Add _Py_FatalErrorFunc() function.
* Remove the function name from the message of Py_FatalError() calls
  which included the function name.
* Update tests.
diff --git a/Parser/parser.c b/Parser/parser.c
index 227b918..a61b2f5 100644
--- a/Parser/parser.c
+++ b/Parser/parser.c
@@ -54,8 +54,9 @@
 static void
 s_pop(stack *s)
 {
-    if (s_empty(s))
-        Py_FatalError("s_pop: parser stack underflow -- FATAL");
+    if (s_empty(s)) {
+        Py_FatalError("parser stack underflow");
+    }
     s->s_top++;
 }