remove configure check for 'volatile' (#3281)

This is a required feature is C99, which we require.

configure

@@ -13543,32 +13543,6 @@ $as_echo "#define const /**/" >>confdefs.h
 fi
 
 
-works=no
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for working volatile" >&5
-$as_echo_n "checking for working volatile... " >&6; }
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-int
-main ()
-{
-volatile int x; x = 0;
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  works=yes
-else
-
-$as_echo "#define volatile /**/" >>confdefs.h
-
-
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $works" >&5
-$as_echo "$works" >&6; }
-
 works=no
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for working signed char" >&5
 $as_echo_n "checking for working signed char... " >&6; }

configure.ac

@@ -4080,14 +4080,6 @@ fi
 AC_C_CHAR_UNSIGNED
 AC_C_CONST
 
-works=no
-AC_MSG_CHECKING(for working volatile)
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[volatile int x; x = 0;]])],
-  [works=yes],
-  [AC_DEFINE(volatile, , [Define to empty if the keyword does not work.])]
-)
-AC_MSG_RESULT($works)
-
 works=no
 AC_MSG_CHECKING(for working signed char)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[signed char c;]])],

pyconfig.h.in

@@ -775,6 +775,9 @@
 /* Define to 1 if you have the `sched_setscheduler' function. */
 #undef HAVE_SCHED_SETSCHEDULER
 
+/* Define to 1 if you have the `select' function. */
+#undef HAVE_SELECT
+
 /* Define to 1 if you have the `sem_getvalue' function. */
 #undef HAVE_SEM_GETVALUE
 
@@ -1505,9 +1508,6 @@
 /* Define to `int' if <sys/types.h> doesn't define. */
 #undef uid_t
 
-/* Define to empty if the keyword does not work. */
-#undef volatile
-
 
 /* Define the macros needed if on a UnixWare 7.x system. */
 #if defined(__USLC__) && defined(__SCO_VERSION__)