openmp: Add testcase for scan directive with nested functions

openmp: Add testcase for scan directive with nested functions

> In convert_nonlocal_omp_clauses, the following clauses are
> missing: OMP_CLAUSE_AFFINITY, OMP_CLAUSE_DEVICE_TYPE,
> OMP_CLAUSE_EXCLUSIVE, OMP_CLAUSE_INCLUSIVE.

OMP_CLAUSE_{EXCLUSIVE,INCLUSIVE} isn't needed, because we don't
walk the clauses at all for GIMPLE_OMP_SCAN.  It would be a bug
if we used the exclusive/inclusive operands after gimplification,
but we apparently don't do that, all we check is whether the
OMP_CLAUSE_KIND of the first clause (all should be the same) is
OMP_CLAUSE_EXCLUSIVE or OMP_CLAUSE_INCLUSIVE, nothing else.

That said, I think we should have a testcase.

2021-06-06  Jakub Jelinek  <jakub@redhat.com>

	* gcc.dg/gomp/scan-1.c: New test.