Fix grammatical typos around possessive "its"

Some places spelled it "it's", which is short for "it is".
In passing, fix a couple other nearby grammatical errors.

Author: Jacob Brazeal <jacob.brazeal@gmail.com>
Discussion: https://postgr.es/m/CA+COZaAO8g1KJCV0T48=CkJMjAnnfTGLWOATz+2aCh40c2Nm+g@mail.gmail.com

src/backend/access/spgist/spgscan.c

@@ -865,7 +865,7 @@ redirect:
 
 			if (SpGistPageIsLeaf(page))
 			{
-				/* Page is a leaf - that is, all it's tuples are heap items */
+				/* Page is a leaf - that is, all its tuples are heap items */
 				OffsetNumber max = PageGetMaxOffsetNumber(page);
 
 				if (SpGistBlockIsRoot(blkno))

src/backend/replication/logical/reorderbuffer.c

@@ -1663,7 +1663,7 @@ ReorderBufferTruncateTXN(ReorderBuffer *rb, ReorderBufferTXN *txn, bool txn_prep
 		/* Check we're not mixing changes from different transactions. */
 		Assert(change->txn == txn);
 
-		/* remove the change from it's containing list */
+		/* remove the change from its containing list */
 		dlist_delete(&change->node);
 
 		/*

src/backend/replication/logical/worker.c

@@ -4092,7 +4092,7 @@ subscription_change_cb(Datum arg, int cacheid, uint32 hashvalue)
  * subxact_info_write
  *	  Store information about subxacts for a toplevel transaction.
  *
- * For each subxact we store offset of it's first change in the main file.
+ * For each subxact we store offset of its first change in the main file.
  * The file is always over-written as a whole.
  *
  * XXX We should only store subxacts that were not aborted yet.

src/backend/replication/pgoutput/pgoutput.c

@@ -1849,7 +1849,7 @@ pgoutput_stream_stop(struct LogicalDecodingContext *ctx,
 
 /*
  * Notify downstream to discard the streamed transaction (along with all
- * it's subtransactions, if it's a toplevel transaction).
+ * its subtransactions, if it's a toplevel transaction).
  */
 static void
 pgoutput_stream_abort(struct LogicalDecodingContext *ctx,
@@ -1882,7 +1882,7 @@ pgoutput_stream_abort(struct LogicalDecodingContext *ctx,
 
 /*
  * Notify downstream to apply the streamed transaction (along with all
- * it's subtransactions).
+ * its subtransactions).
  */
 static void
 pgoutput_stream_commit(struct LogicalDecodingContext *ctx,

src/backend/storage/lmgr/lock.c

@@ -1323,7 +1323,7 @@ SetupLockInTable(LockMethod lockMethodTable, PGPROC *proc,
 		 * on our own behalf, in which case our group leader isn't changing
 		 * because the group leader for a process can only ever be changed by
 		 * the process itself; or else we are transferring a fast-path lock to
-		 * the main lock table, in which case that process can't change it's
+		 * the main lock table, in which case that process can't change its
 		 * lock group leader without first releasing all of its locks (and in
 		 * particular the one we are currently transferring).
 		 */

src/backend/storage/lmgr/lwlock.c

@@ -60,7 +60,7 @@
  * The attentive reader might have noticed that naively doing the above has a
  * glaring race condition: We try to lock using the atomic operations and
  * notice that we have to wait. Unfortunately by the time we have finished
- * queuing, the former locker very well might have already finished it's
+ * queuing, the former locker very well might have already finished its
  * work. That's problematic because we're now stuck waiting inside the OS.
 
  * To mitigate those races we use a two phased attempt at locking:

src/backend/utils/adt/formatting.c

@@ -5561,7 +5561,7 @@ NUM_numpart_from_char(NUMProc *Np, int id, int input_len)
 		}
 
 		/*
-		 * try read non-locale sign, it's happen only if format is not exact
+		 * try read non-locale sign, which happens only if format is not exact
 		 * and we cannot determine sign position of MI/PL/SG, an example:
 		 *
 		 * FM9.999999MI			   -> 5.01-

src/backend/utils/adt/jsonpath_exec.c

@@ -77,7 +77,7 @@
 #include "utils/timestamp.h"
 
 /*
- * Represents "base object" and it's "id" for .keyvalue() evaluation.
+ * Represents "base object" and its "id" for .keyvalue() evaluation.
  */
 typedef struct JsonBaseObjectInfo
 {

src/backend/utils/adt/tsrank.c

@@ -812,7 +812,7 @@ get_docrep(TSVector txt, QueryRepresentation *qr, int *doclen)
 		qsort(doc, cur, sizeof(DocRepresentation), compareDocR);
 
 		/*
-		 * Join QueryItem per WordEntry and it's position
+		 * Join QueryItem per WordEntry and its position
 		 */
 		storage.pos = doc->pos;
 		storage.data.query.items = palloc(sizeof(QueryItem *) * qr->query->size);

src/backend/utils/sort/tuplesort.c

@@ -202,7 +202,7 @@ struct Tuplesortstate
 	int64		maxSpace;		/* maximum amount of space occupied among sort
 								 * of groups, either in-memory or on-disk */
 	bool		isMaxSpaceDisk; /* true when maxSpace is value for on-disk
-								 * space, false when it's value for in-memory
+								 * space, false when its value for in-memory
 								 * space */
 	TupSortStatus maxSpaceStatus;	/* sort status when maxSpace was reached */
 	LogicalTapeSet *tapeset;	/* logtape.c object for tapes in a temp file */