gh-112136: Remove unused #include "pycore_lock.h" (#127093)

pycore_modsupport.h no longer needs pycore_lock.h.

Author: vstinner

Include/internal/pycore_modsupport.h

@@ -1,8 +1,6 @@
 #ifndef Py_INTERNAL_MODSUPPORT_H
 #define Py_INTERNAL_MODSUPPORT_H
 
-#include "pycore_lock.h"    // _PyOnceFlag
-
 #ifdef __cplusplus
 extern "C" {
 #endif