[Flang]Fix propagation of loop collapse number for target-based directives (llvm#162707)

Author: alexey-bataev

flang/lib/Lower/OpenMP/OpenMP.cpp

@@ -153,6 +153,7 @@ class HostEvalInfo {
     clauseOps.loopLowerBounds = ops.loopLowerBounds;
     clauseOps.loopUpperBounds = ops.loopUpperBounds;
     clauseOps.loopSteps = ops.loopSteps;
+    clauseOps.collapseNumLoops = ops.collapseNumLoops;
     ivOut.append(iv);
     return true;
   }

flang/test/Lower/OpenMP/distribute-parallel-do-simd.f90

@@ -112,7 +112,7 @@ subroutine lastprivate_cond_in_composite_construct(x_min, x_max, y_min, y_max)
 ! CHECK:                 omp.distribute {
 ! CHECK:                   omp.wsloop {
 ! CHECK:                     omp.simd private({{.*}}) {
-! CHECK:                       omp.loop_nest (%[[I_IV:.*]], %[[J_IV:.*]]) : i32 = ({{.*}}) to ({{.*}}) inclusive step ({{.*}}) {
+! CHECK:                       omp.loop_nest (%[[I_IV:.*]], %[[J_IV:.*]]) : i32 = ({{.*}}) to ({{.*}}) inclusive step ({{.*}}) collapse(2) {
 ! CHECK:                         %[[Y_MAX_PRIV:.*]]:2 = hlfir.declare %{{.*}} {uniq_name = "{{.*}}y_max"}
 
 ! CHECK:                         %[[I_UB:.*]] = fir.load %[[X_MAX_MAPPED]]#0 : !fir.ref<i32>