Add test

Author: tblah

flang/test/Lower/OpenMP/clause-cleanup.f90

@@ -0,0 +1,17 @@
+!RUN: %flang_fc1 -emit-hlfir -fopenmp %s -o - | FileCheck %s
+
+subroutine test1(a)
+integer :: a(:)
+
+!$omp parallel num_threads(count(a .eq. 1))
+print *, "don't optimize me"
+!$omp end parallel
+end subroutine
+
+! CHECK:     %[[EXPR:.*]] = hlfir.elemental {{.*}} -> !hlfir.expr<?x!fir.logical<4>>
+! CHECK:     %[[COUNT:.*]] = hlfir.count %[[EXPR]]
+! CHECK:     omp.parallel num_threads(%[[COUNT]] : i32) {
+! CHECK-NOT:   hlfir.destory %[[EXPR]]
+! CHECK:     omp.terminator
+! CHECK:    }
+! CHECK:    hlfir.destroy %[[EXPR]]