x86/crtools: Add fork() err-path handle

Error-path for failed fork().
Looks originally forgotten, oops!
Also print a message on failed fork().
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/arch/x86/crtools.c

@@ -40,8 +40,10 @@ int kdat_can_map_vdso(void)
 	 * it for criu accidentally.
 	 */
 	child = fork();
-	if (child < 0)
+	if (child < 0) {
+		pr_perror("%s(): failed to fork()", __func__);
 		return -1;
+	}
 
 	if (child == 0) {
 		int ret;
@@ -150,6 +152,11 @@ static int has_32bit_mmap_bug(void)
 	pid_t child = fork();
 	int stat;
 
+	if (child < 0) {
+		pr_perror("%s(): failed to fork()", __func__);
+		return -1;
+	}
+
 	if (child == 0)
 		mmap_bug_test();