Fix multi-block spanning libcall sequence

[Arnaud Charlet]

> I think that the GNAT dg testsuite should only contain reduced testcases,
> like 
> the dg testsuite of other compilers.  ACATS tests are definitely not reduced, 
> the first thing I do when investigating an ACATS failure is to reduce the 
> test.  And my experience is that it's always doable with a bit of work.

Well fine with me, if that's how people feel this directory should be.

Arno