Null terminate argv array in Go land not C land

proc/exec_darwin.c

@@ -12,8 +12,6 @@ fork_exec(char *argv0, char **argv, int size,
 	int fd[2];
 	if (pipe(fd) < 0) return -1;
 
-	argv[size-1] = '\0';
-
 	kern_return_t kret;
 	pid_t pid = fork();
 	if (pid > 0) {

proc/proc_darwin.go

@@ -50,16 +50,19 @@ func Launch(cmd []string) (*Process, error) {
 	}
 
 	argv0 := C.CString(argv0Go)
-
 	argvSlice := make([]*C.char, 0, len(cmd)+1)
 	for _, arg := range cmd {
 		argvSlice = append(argvSlice, C.CString(arg))
 	}
+	// argv array must be null terminated.
+	argvSlice = append(argvSlice, nil)
 
 	dbp := New(0)
 	var pid int
 	dbp.execPtraceFunc(func() {
-		ret := C.fork_exec(argv0, &argvSlice[0], C.int(len(argvSlice)), &dbp.os.task, &dbp.os.portSet, &dbp.os.exceptionPort, &dbp.os.notificationPort)
+		ret := C.fork_exec(argv0, &argvSlice[0], C.int(len(argvSlice)),
+			&dbp.os.task, &dbp.os.portSet, &dbp.os.exceptionPort,
+			&dbp.os.notificationPort)
 		pid = int(ret)
 	})
 	if pid <= 0 {