Added missing config.[ch] lines for FTP protocol

src/config.h

 #define	DOWNLOAD_PROTO_TFTP	/* Trivial File Transfer Protocol */
 #undef	DOWNLOAD_PROTO_NFS	/* Network File System */
 #define	DOWNLOAD_PROTO_HTTP	/* Hypertext Transfer Protocol */
+#undef	DOWNLOAD_PROTO_FTP	/* File Transfer Protocol */
 #undef	DOWNLOAD_PROTO_TFTM	/* Multicast Trivial File Transfer Protocol */
 #undef	DOWNLOAD_PROTO_SLAM	/* Scalable Local Area Multicast */
 #undef	DOWNLOAD_PROTO_FSP	/* FSP? */

src/core/config.c

 #ifdef DOWNLOAD_PROTO_HTTP
 REQUIRE_OBJECT ( http );
 #endif
+#ifdef DOWNLOAD_PROTO_FTP
+REQUIRE_OBJECT ( ftp );
+#endif
 #ifdef DOWNLOAD_PROTO_TFTM
 REQUIRE_OBJECT ( tftm );
 #endif