gnat changes for gcc-4.9

[Matthias Klose <doko@debian.org>]

Hi,

thanks for merging back the Ada changes. r7211 did basically remove the 
go-use-gold.diff patch, which I did undo again.

upstream now has zcx exception support for ARM, so would it be possible to drop 
the sjlj based exception support for the jessie release?  Is anybody using this 
on platforms where the zcx support is available? Asking because the current 
support isn't good enough for cross-building the package.

Also is there any progress in upstreaming the libgnatproj* additions?

Thanks, Matthias