Add a simple unix controller

Signed-off-by: Adrien Gallouët <adrien@gallouet.fr>

src/ctl.h

@@ -0,0 +1,19 @@
+#pragma once
+
+enum ctl_type {
+    CTL_UNKNOWN,
+    CTL_PING,
+    CTL_PONG,
+};
+
+struct ctl_msg {
+    enum ctl_type type;
+    union {
+        struct {
+            enum ctl_type type;
+        } unknown;
+    };
+};
+
+int ctl_init    (const char *, const char *);
+int ctl_connect (int, const char *, const char *);