Return a string (even though abort is called first) to pacify gcc.

svn path=/trunk/; revision=35724

wiretap/file_access.c

@@ -670,6 +670,7 @@ const char *wtap_file_type_string(int filetype)
 	if (filetype < 0 || filetype >= wtap_num_file_types) {
 		g_error("Unknown capture file type %d", filetype);
 		/** g_error() does an abort() and thus never returns **/
+		return "";
 	} else
 		return dump_open_table[filetype].name;
 }