Check error code of fork(2).

Index: conformance/interfaces/sigsuspend/6-1.c
--- conformance/interfaces/sigsuspend/6-1.c.orig
+++ conformance/interfaces/sigsuspend/6-1.c
@@ -33,9 +33,12 @@ void handler(int signo)
 int main()
 {
 	pid_t pid;
-	pid = fork();
 
-	if (pid == 0) {
+	pid = fork();
+	if (pid == -1) {
+		perror("fork");
+		return PTS_UNRESOLVED;
+	} else if (pid == 0) {
 		/* child */
 
 	        sigset_t tempmask;
