Python.h: Don't attempt to redefine NDEBUG if it's already defined.

Others:  Remove redundant includes of assert.h.

Include/Python.h

@@ -51,8 +51,10 @@
 #endif
 
 #ifndef Py_DEBUG
+#ifndef NDEBUG
 #define NDEBUG 1
 #endif
+#endif
 #include <assert.h>
 
 #include "pyport.h"

Modules/mpzmodule.c

@@ -12,7 +12,6 @@
 
 #include "Python.h"
 
-#include <assert.h>
 #include <sys/types.h>		/* For size_t */
 
 /*

Modules/regexpr.c

@@ -30,7 +30,6 @@
 
 #include "Python.h"
 #include "regexpr.h"
-#include <assert.h>
 
 /* The original code blithely assumed that sizeof(short) == 2.  Not
  * always true.  Original instances of "(short)x" were replaced by

Objects/longobject.c

@@ -6,7 +6,6 @@
 #include "Python.h"
 #include "longintrepr.h"
 
-#include <assert.h>
 #include <ctype.h>
 
 #define ABS(x) ((x) < 0 ? -(x) : (x))

PC/import_nt.c

@@ -8,7 +8,6 @@
 
 #include "Python.h"
 #include "osdefs.h"
-#include <assert.h>
 #include <windows.h>
 #include "importdl.h"
 #include "malloc.h" /* for alloca */