initctl refactor, break out domain socket/client API

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

src/client.h

@@ -0,0 +1,39 @@
+/* External client API, using UNIX domain socket.
+ *
+ * Copyright (c) 2015-2017  Joachim Nilsson <troglobit@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef FINIT_CLIENT_H_
+#define FINIT_CLIENT_H_
+
+#include "finit.h"
+
+typedef struct {
+	char  *cmd;
+	int  (*cb)(char *arg);
+} command_t;
+
+int client_connect    (void);
+int client_disconnect (void);
+
+int client_send       (struct init_request *rq, ssize_t len);
+
+#endif /* FINIT_CLIENT_H_ */