Removed unused block_t->p_prev field.

include/vlc_block.h

@@ -95,7 +95,6 @@ typedef void (*block_free_t) (block_t *);
 struct block_t
 {
     block_t     *p_next;
-    block_t     *p_prev;
 
     uint32_t    i_flags;
 

src/misc/block.c

@@ -57,7 +57,7 @@ static void BlockNoRelease( block_t *b )
 void block_Init( block_t *restrict b, void *buf, size_t size )
 {
     /* Fill all fields to their default */
-    b->p_next = b->p_prev = NULL;
+    b->p_next = NULL;
     b->i_flags = 0;
     b->i_pts = b->i_dts = b->i_length = 0;
     b->i_rate = 0;