misc/cgo/testsigfwd: delete unused code

This code was introduced in CL 17903 but has never executed. It's also
fundamentally non-deterministic. Delete it.

Simplification for #37486.

Change-Id: I049564123fb4fba401154e2ea0fc429e552d4749
Reviewed-on: https://go-review.googlesource.com/c/go/+/431258
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

misc/cgo/testsigfwd/main.go

@@ -7,14 +7,10 @@ package main
 import "fmt"
 
 /*
-#cgo CFLAGS: -pthread
-#cgo LDFLAGS: -pthread
-
 #include <signal.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <pthread.h>
 
 int *p;
 static void sigsegv() {
@@ -30,60 +26,12 @@ static void segvhandler(int signum) {
 	}
 }
 
-static volatile sig_atomic_t sigioSeen;
-
-// Use up some stack space.
-static void recur(int i, char *p) {
-	char a[1024];
-
-	*p = '\0';
-	if (i > 0) {
-		recur(i - 1, a);
-	}
-}
-
-static void iohandler(int signum) {
-	char a[1024];
-
-	recur(4, a);
-	sigioSeen = 1;
-}
-
-static void* sigioThread(void* arg __attribute__ ((unused))) {
-	raise(SIGIO);
-	return NULL;
-}
-
-static void sigioOnThread() {
-	pthread_t tid;
-	int i;
-
-	pthread_create(&tid, NULL, sigioThread, NULL);
-	pthread_join(tid, NULL);
-
-	// Wait until the signal has been delivered.
-	i = 0;
-	while (!sigioSeen) {
-		if (sched_yield() < 0) {
-			perror("sched_yield");
-		}
-		i++;
-		if (i > 10000) {
-			fprintf(stderr, "looping too long waiting for signal\n");
-			exit(EXIT_FAILURE);
-		}
-	}
-}
-
 static void __attribute__ ((constructor)) sigsetup(void) {
 	struct sigaction act;
 
 	memset(&act, 0, sizeof act);
 	act.sa_handler = segvhandler;
 	sigaction(SIGSEGV, &act, NULL);
-
-	act.sa_handler = iohandler;
-	sigaction(SIGIO, &act, NULL);
 }
 */
 import "C"