reader: remove unused archive_read_filter callbacks

In particular the ::open and ::sswitch callbacks are unused.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

Author: evelikov

libarchive/archive_read.c

@@ -486,10 +486,8 @@ archive_read_open1(struct archive *_a)
 	filter->upstream = NULL;
 	filter->archive = a;
 	filter->data = a->client.dataset[0].data;
-	filter->open = client_open_proxy;
 	filter->read = client_read_proxy;
 	filter->close = client_close_proxy;
-	filter->sswitch = client_switch_proxy;
 	filter->name = "none";
 	filter->code = ARCHIVE_FILTER_NONE;
 	filter->can_skip = 1;

libarchive/archive_read_private.h

@@ -87,14 +87,10 @@ struct archive_read_filter {
 	struct archive_read_filter_bidder *bidder; /* My bidder. */
 	struct archive_read_filter *upstream; /* Who I read from. */
 	struct archive_read *archive; /* Associated archive. */
-	/* Open a block for reading */
-	int (*open)(struct archive_read_filter *self);
 	/* Return next block. */
 	ssize_t (*read)(struct archive_read_filter *, const void **);
 	/* Close (just this filter) and free(self). */
 	int (*close)(struct archive_read_filter *self);
-	/* Function that handles switching from reading one block to the next/prev */
-	int (*sswitch)(struct archive_read_filter *self, unsigned int iindex);
 	/* Read any header metadata if available. */
 	int (*read_header)(struct archive_read_filter *self, struct archive_entry *entry);
 	/* My private data. */