remove IRIX support (closes bpo-31341) (#3310)

See PEP 11.

Modules/Setup.dist

@@ -350,9 +350,6 @@ _symtable symtablemodule.c
 # The library to link fpectl with is platform specific.
 # Choose *one* of the options below for fpectl:
 
-# For SGI IRIX (tested on 5.3):
-#fpectl fpectlmodule.c -lfpe
-
 # For Solaris with SunPro compiler (tested on Solaris 2.5 with SunPro C 4.2):
 # (Without the compiler you don't have -lsunmath.)
 #fpectl fpectlmodule.c -R/opt/SUNWspro/lib -lsunmath -lm

Modules/fpectlmodule.c

@@ -111,29 +111,8 @@ static void fpe_reset(Sigfunc *handler)
      * handler for SIGFPE to the given handler.
      */
 
-/*-- IRIX -----------------------------------------------------------------*/
-#if defined(sgi)
-    /* See man page on handle_sigfpes -- must link with -lfpe
-     * My usage doesn't follow the man page exactly.  Maybe somebody
-     * else can explain handle_sigfpes to me....
-     * cc -c -I/usr/local/python/include fpectlmodule.c
-     * ld -shared -o fpectlmodule.so fpectlmodule.o -lfpe
-     */
-#include <sigfpe.h>
-    typedef void user_routine (unsigned[5], int[2]);
-    typedef void abort_routine (unsigned long);
-    handle_sigfpes(_OFF, 0,
-                 (user_routine *)0,
-                 _TURN_OFF_HANDLER_ON_ERROR,
-                 NULL);
-    handle_sigfpes(_ON, _EN_OVERFL | _EN_DIVZERO | _EN_INVALID,
-                 (user_routine *)0,
-                 _ABORT_ON_ERROR,
-                 NULL);
-    PyOS_setsig(SIGFPE, handler);
-
 /*-- SunOS and Solaris ----------------------------------------------------*/
-#elif defined(sun)
+#if defined(sun)
     /* References: ieee_handler, ieee_sun, ieee_functions, and ieee_flags
        man pages (SunOS or Solaris)
        cc -c -I/usr/local/python/include fpectlmodule.c

Modules/socketmodule.c

@@ -268,10 +268,8 @@ if_indextoname(index) -- return the corresponding interface name\n\
 #include <netdb.h>
 #endif
 
-/* Irix 6.5 fails to define this variable at all. This is needed
-   for both GCC and SGI's compiler. I'd say that the SGI headers
-   are just busted. Same thing for Solaris. */
-#if (defined(__sgi) || defined(sun)) && !defined(INET_ADDRSTRLEN)
+/* Solaris fails to define this variable at all. */
+#if defined(sun) && !defined(INET_ADDRSTRLEN)
 #define INET_ADDRSTRLEN 16
 #endif