runtime: correct GoCheckBindM's C declaration in EnsureBindM test

The test file has a C declaration which doesn't match the actual
definition. Remove it and include "_cgo_export.h" to have the
right declaration.

Change-Id: Iddf6d8883ee0e439147c7027029dd3e352ef090d
Reviewed-on: https://go-review.googlesource.com/c/go/+/482975
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

Author: cherrymui

src/runtime/testdata/testprogcgo/bindm.c

@@ -0,0 +1,34 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !plan9 && !windows
+
+#include <stdint.h>
+#include <pthread.h>
+#include <unistd.h>
+#include "_cgo_export.h"
+
+#define CTHREADS 2
+#define CHECKCALLS 100
+
+static void* checkBindMThread(void* thread) {
+	int i;
+	for (i = 0; i < CHECKCALLS; i++) {
+		GoCheckBindM((uintptr_t)thread);
+		usleep(1);
+	}
+	return NULL;
+}
+
+void CheckBindM() {
+	int i;
+	pthread_t s[CTHREADS];
+
+	for (i = 0; i < CTHREADS; i++) {
+		pthread_create(&s[i], NULL, checkBindMThread, &s[i]);
+	}
+	for (i = 0; i < CTHREADS; i++) {
+		pthread_join(s[i], NULL);
+	}
+}

src/runtime/testdata/testprogcgo/bindm.go

@@ -10,35 +10,7 @@
 package main
 
 /*
-#include <stdint.h>
-#include <pthread.h>
-#include <unistd.h>
-
-extern void GoCheckBindM();
-
-#define CTHREADS 2
-#define CHECKCALLS 100
-
-static void* checkBindMThread(void* thread) {
-	int i;
-	for (i = 0; i < CHECKCALLS; i++) {
-		GoCheckBindM((uintptr_t)thread);
-		usleep(1);
-	}
-	return NULL;
-}
-
-static void CheckBindM() {
-	int i;
-	pthread_t s[CTHREADS];
-
-	for (i = 0; i < CTHREADS; i++) {
-		pthread_create(&s[i], NULL, checkBindMThread, &s[i]);
-	}
-	for (i = 0; i < CTHREADS; i++) {
-		pthread_join(s[i], NULL);
-	}
-}
+extern void CheckBindM();
 */
 import "C"