Quote prepared statements of `sanitize_sql_array`

Sure unquoted SQL code pass test, but this % style prepared statements
are dangerous. Test codes and code examples are also "Rails" codes,
so quote placeholder of prepared statements.

activerecord/test/cases/sanitize_test.rb

@@ -9,11 +9,11 @@ def setup
 
   def test_sanitize_sql_array_handles_string_interpolation
     quoted_bambi = ActiveRecord::Base.connection.quote_string("Bambi")
-    assert_equal "name=#{quoted_bambi}", Binary.send(:sanitize_sql_array, ["name=%s", "Bambi"])
-    assert_equal "name=#{quoted_bambi}", Binary.send(:sanitize_sql_array, ["name=%s", "Bambi".mb_chars])
+    assert_equal "name='#{quoted_bambi}'", Binary.send(:sanitize_sql_array, ["name='%s'", "Bambi"])
+    assert_equal "name='#{quoted_bambi}'", Binary.send(:sanitize_sql_array, ["name='%s'", "Bambi".mb_chars])
     quoted_bambi_and_thumper = ActiveRecord::Base.connection.quote_string("Bambi\nand\nThumper")
-    assert_equal "name=#{quoted_bambi_and_thumper}",Binary.send(:sanitize_sql_array, ["name=%s", "Bambi\nand\nThumper"])
-    assert_equal "name=#{quoted_bambi_and_thumper}",Binary.send(:sanitize_sql_array, ["name=%s", "Bambi\nand\nThumper".mb_chars])
+    assert_equal "name='#{quoted_bambi_and_thumper}'",Binary.send(:sanitize_sql_array, ["name='%s'", "Bambi\nand\nThumper"])
+    assert_equal "name='#{quoted_bambi_and_thumper}'",Binary.send(:sanitize_sql_array, ["name='%s'", "Bambi\nand\nThumper".mb_chars])
   end
 
   def test_sanitize_sql_array_handles_bind_variables