Update su request process

Due to changes in ec3705f2ed, the app can
no longer communicate with the dameon through a socket opened on the
daemon side due to SELinux restrictions. The workaround here is to have
the daemon decide a socket name, send it to the app, have the app create
the socket server, then finally the daemon connects to the app through
the socket.

native/jni/utils/files.hpp

@@ -133,3 +133,7 @@ static inline sFILE open_file(const char *path, const char *mode) {
 static inline sFILE xopen_file(const char *path, const char *mode) {
 	return sFILE(xfopen(path, mode), fclose);
 }
+
+static inline sFILE xopen_file(int fd, const char *mode) {
+	return sFILE(xfdopen(fd, mode), fclose);
+}