Log Message:
databases/ruby-activerecord51: update to 5.1.7

Update ruby-activerecord51 to 5.1.7.

pkgsrc change: add "USE_LANGAUGES=	# none".

## Rails 5.1.7 (March 27, 2019) ##

*   Fix `touch` option to behave consistently with `Persistence#touch` method.

    *Ryuta Kamizono*

*   Back port Rails 5.2 `reverse_order` Arel SQL literal fix.

    *Matt Jones*, *Brooke Kuhlmann*

*   `becomes` should clear the mutation tracker which is created in \ 
`after_initialize`.

    Fixes #32867.

    *Ryuta Kamizono*