Fixes for single-page hash index vacuum.

Clear LH_PAGE_HAS_DEAD_TUPLES during replay, similar to what gets done
for btree.  Update hashdesc.c for xl_hash_vacuum_one_page.

Oversights in commit 6977b8b7f4 spotted
by Amit Kapila.  Patch by Ashutosh Sharma.

Bump WAL version.  The original patch to make hash indexes write-ahead
logged probably should have done this, and the single page vacuuming
patch probably should have done it again, but better late than never.

Discussion: http://postgr.es/m/CAA4eK1Kd=mJ9xreovcsh0qMiAj-QqCphHVQ_Lfau1DR9oVjASQ@mail.gmail.com

src/include/access/hash_xlog.h

@@ -197,6 +197,8 @@ typedef struct xl_hash_squeeze_page
  */
 typedef struct xl_hash_delete
 {
+	bool		clear_dead_marking;		/* TRUE if this operation clears
+										 * LH_PAGE_HAS_DEAD_TUPLES flag */
 	bool		is_primary_bucket_page; /* TRUE if the operation is for
 										 * primary bucket page */
 }	xl_hash_delete;