[Ada] Fix comment typo in exp_ch9.adb

[Arnaud Charlet]

OK, thanks.

> Index: gcc/ada/ChangeLog
> ===================================================================
> 
> --- gcc/ada/ChangeLog   (revision 264438)
> +++ gcc/ada/ChangeLog   (working copy)
> @@ -1,3 +1,7 @@
> +2018-09-20  Oliver Kellogg  <olivermkellogg@gmail.com>
> +
> +       * exp_ch9.adb: Fix typo 'geenrated' to 'generated'.
> +
>  2018-09-13  Eric Botcazou  <ebotcazou@adacore.com>
> 
>         * Makefile.rtl (arm% linux-gnueabi%): Always set EH_MECHANISM
>         to -arm.
> Index: gcc/ada/exp_ch9.adb
> ===================================================================
> 
> --- gcc/ada/exp_ch9.adb (revision 264438)
> +++ gcc/ada/exp_ch9.adb (working copy)
> @@ -481,7 +481,7 @@
>     --  to be E. Bod is either a block or a subprogram body.  Used after
>     --  expanding various kinds of entry bodies into their corresponding
>     --  constructs. This is needed during unnesting to determine whether a
> -   --  body geenrated for an entry or an accept alternative includes uplevel
> +   --  body generated for an entry or an accept alternative includes uplevel
>     --  references.
> 
>     function Trivial_Accept_OK return Boolean;
>