In extensions rtree, fts3 and fts5, ensure that when dynamic buffers are bound

to persistent SQL statements using SQLITE_STATIC, the binding is replaced with
an SQL NULL before the buffer is freed. Otherwise, a user may obtain a pointer
to the persistent statement using sqlite3_next_stmt() and attempt to access
the freed buffer using sqlite3_expanded_sql() or similar.

FossilOrigin-Name: 2a5f813bc61f9e780f2ccbda425611f65ad523b6d486a1e5e2b9d5e9f1d260a2

ext/rtree/rtree6.test

@@ -158,5 +158,5 @@ do_execsql_test rtree6-3.5 {
     x1>0.5 AND x1>0.5 AND x1>0.5 AND x1>0.5 AND x1>1.1
 } {}
 
-
+expand_all_sql db
 finish_test