add accidentally-omitted file needed for posix_spawn file actions

src/process/fdop.h

+#define FDOP_CLOSE 1
+#define FDOP_DUP2 2
+#define FDOP_OPEN 3
+
+struct fdop {
+	struct fdop *next;
+	int cmd, fd, newfd, oflag;
+	mode_t mode;
+	char path[];
+};