gh-110079: Remove extern "C" { ...} in C code (#110080)

Python/pythonrun.c

@@ -37,11 +37,6 @@
 #  include "windows.h"
 #endif
 
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 /* Forward */
 static void flush_io(void);
 static PyObject *run_mod(mod_ty, PyObject *, PyObject *, PyObject *,
@@ -2017,7 +2012,3 @@ PyRun_InteractiveLoop(FILE *f, const char *p)
 {
     return PyRun_InteractiveLoopFlags(f, p, NULL);
 }
-
-#ifdef __cplusplus
-}
-#endif