bpo-35064 prefix smelly symbols that appear with COUNT_ALLOCS with _Py_ (GH-10152)

Configuring python with ./configure --with-pydebug CFLAGS="-D COUNT_ALLOCS -O0"
makes "make smelly" fail as some symbols were being exported without the "Py_" or
"_Py" prefixes.

Python/sysmodule.c

@@ -1340,9 +1340,9 @@ size."
 static PyObject *
 sys_getcounts(PyObject *self)
 {
-    extern PyObject *get_counts(void);
+    extern PyObject *_Py_get_counts(void);
 
-    return get_counts();
+    return _Py_get_counts();
 }
 #endif