[tree-ssa PATCH] Kill RTL never_reached_warning

[Arnaud Charlet]

> Bootstrapped-'n-tested c,c++,objc,f95.  OK?

No objection, GNAT has indeed its own handling of unreachable code,
and as pointed out, does not build on tree-ssa, although this is not per-se
a reason for making things harder for Ada in general.

Arno