removed fdprintf() and client_print()

All callers of fdprintf() have been converted to client_printf() or
fprintf(); it is time to remove this clumsy hack now.  We can also
remove client_print() which took a file descriptor as parameter.

src/client.h

@@ -53,6 +53,4 @@ void client_vprintf(struct client *client, const char *fmt, va_list args);
  */
 mpd_fprintf void client_printf(struct client *client, const char *fmt, ...);
 
-int client_print(int fd, const char *buffer, size_t len);
-
 #endif