[patch ada] Use Ada output of gnatbind for building tools

[Eric Botcazou]

> gnatbind can generate Ada or C output.  The C output is being deprecated so
> it shouldn't be used to build the tools. This patch updates the Makefiles
> so that the Ada output is used instead.

Great!  Please mention PR ada/44431 in the ChangeLog.

-- 
Eric Botcazou