gnat-4.9

[Nicolas Boulenguez <nicolas.boulenguez@free.fr>]

Hello.
Congratulations, head of the gnat-4.9 branch builds on amd64!

Here is a survey covering most of the bugs reported against gnat-4.y.
Most of them persist in 4.9: 244936, 244970, 246183, 246187, 247013,
247017, 247018, 247019, 247569, 247570, 247571, 248166, 248168,
248678, 248680, 248681, 248682, 253737, 269948, 269951, 276224,
276227, 278687, 278831, 279893, 280939, 283833, 283835, 416979,
660698, 737225.
One still fails, but with a different message: 427108.
Two used to complain on legal code, and now crash: 247564, 251265.
And two are fixed: 246186, 416975.

I have tried to build some packages, everythings seems ok without
refreshing one single patch: asis (2013), dh-ada-library (with all
warnings), libxmlada (quite old version though), libgmpada (with all
warnings), ada-reference-manual.

Maybe gnat-4.9 should conflict with gnat-4.8, at least until we are
bored playing with them and one is selected for unstable.

Maybe gnat-4.9 should be named gnat4.9 instead, because policy 5.6.12
forbids hyphens in native package names.

Only warnings have changed a lot:
* Either -gnatwa should not activate -gnatw.i, or the online
  documentation should be modified accordingly.
* I think that the new -gnatw.y warning should not be activated by
  -gnatwa, as it produces a lot of noise for a very rare use case.