Improve indenting in _hash_pgaddtup

The Assert added in d09dbeb came out rather ugly after having run
pgindent on that code.  Here we adjust things to use some local variables
so that the Assert remains within the 80-character margin.

Author: Ted Yu
Discussion: https://postgr.es/m/CALte62wLSir1=x93Jf0xZvHaO009FEJfhVMFwnaR8q=csPP8kQ@mail.gmail.com

Author: david-rowley

src/backend/access/hash/hashinsert.c

@@ -290,12 +290,20 @@ _hash_pgaddtup(Relation rel, Buffer buf, Size itemsize, IndexTuple itup,
 	{
 		itup_off = PageGetMaxOffsetNumber(page) + 1;
 
+#ifdef USE_ASSERT_CHECKING
 		/* ensure this tuple's hashkey is >= the final existing tuple */
-		Assert(PageGetMaxOffsetNumber(page) == 0 ||
-			   _hash_get_indextuple_hashkey((IndexTuple)
-											PageGetItem(page, PageGetItemId(page,
-																			PageGetMaxOffsetNumber(page)))) <=
-			   _hash_get_indextuple_hashkey(itup));
+		if (PageGetMaxOffsetNumber(page) > 0)
+		{
+			IndexTuple	lasttup;
+			ItemId		itemid;
+
+			itemid = PageGetItemId(page, PageGetMaxOffsetNumber(page));
+			lasttup = (IndexTuple) PageGetItem(page, itemid);
+
+			Assert(_hash_get_indextuple_hashkey(lasttup) <=
+				   _hash_get_indextuple_hashkey(itup));
+		}
+#endif
 	}
 	else
 	{