gh-110014: Include explicitly <unistd.h> header (#110155)

* Remove unused <locale.h> includes.
* Remove unused <fcntl.h> include in traceback.h.
* Remove redundant <assert.h> and <stddef.h> includes. They  are already
  included by "Python.h".
* Remove <object.h> include in faulthandler.c. Python.h already includes it.
* Add missing <stdbool.h> in pycore_pythread.h if HAVE_PTHREAD_STUBS
  is defined.
* Fix also warnings in pthread_stubs.h: don't redefine macros if they
  are already defined, like the __NEED_pthread_t macro.

Parser/tokenizer.c

@@ -4,10 +4,12 @@
 #include "Python.h"
 #include "pycore_call.h"          // _PyObject_CallNoArgs()
 
-#include <assert.h>
+#include "tokenizer.h"            // struct tok_state
+#include "errcode.h"              // E_OK
 
-#include "tokenizer.h"
-#include "errcode.h"
+#ifdef HAVE_UNISTD_H
+#  include <unistd.h>             // read()
+#endif
 
 /* Alternate tab spacing */
 #define ALTTABSIZE 1