The Ada f-e produces various auxiliary output files

The Ada f-e produces various auxiliary output files
that cannot be suppressed and cannot be redirected:
they are dumped in the current working directory.
When running the testsuite this means that these
files do not end up in the Output directory.  The
best solution I could find is to change directory
into Output before running tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40437 91177308-0d34-0410-b5e6-96231b3b80d8