src/platforms: move remaining source files to platforms/common

platforms/common/apps.h.in

@@ -0,0 +1,16 @@
+/* declarations of builtin command list - automatically generated, do not edit */
+
+#pragma once
+
+#include "px4_tasks.h"	// px4_main_t
+#include <map>
+#include <string>
+
+// Maps an app name to it's function.
+typedef std::map<std::string, px4_main_t> apps_map_type;
+
+// Initialize an apps map.
+__EXPORT void init_app_map(apps_map_type &apps);
+
+// List an apps map.
+__EXPORT void list_builtins(apps_map_type &apps);