Ensure b-tree mutexes are always held when sqlite3FindTable() is called. Do

not invoke the authorizer callback when parsing schema items as part of ALTER
TABLE commands. Fix test script issues.

FossilOrigin-Name: eac2aa7dce577f1998cc2078dd8ac384070f8acf1ceb565999a5cf719092024e

test/fkey2.test

@@ -983,7 +983,7 @@ ifcapable altertable {
   # Test the sqlite_rename_parent() function directly.
   #
   proc test_rename_parent {zCreate zOld zNew} {
-    db eval {SELECT sqlite_rename_parent($zCreate, $zOld, $zNew)}
+    db eval {SELECT sqlite_rename_table('main', $zCreate, $zOld, $zNew, 0)}
   }
   do_test fkey2-14.2.1.1 {
     test_rename_parent {CREATE TABLE t1(a REFERENCES t2)} t2 t3