[Ada] Add support for Ada code generator
[Ada] Add support for Ada code generator

Fix generat_or(), generate_do() to setup a new failure_str and restore
it at the end if necessary.

snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball