[Flang][OpenMP][NFC] Add tests for align and allocator in allocate clauses (#121356)

No functional change.

(Also, tried to filter out all ALLOCATOR modifiers, but that makes some
other tests fail).

Author: Leporacanthicus

flang/test/Lower/OpenMP/Todo/allocate-clause-align.f90

@@ -0,0 +1,13 @@
+! RUN: %not_todo_cmd %flang_fc1 -emit-fir -fopenmp -fopenmp-version=51 -o - %s 2>&1 | FileCheck %s
+
+! CHECK: not yet implemented: OmpAllocateClause ALIGN modifier
+program p
+  integer :: x
+  integer :: a
+  integer :: i
+  !$omp parallel private(x) allocate(align(4): x)
+  do i=1,10
+     a = a + i
+  end do
+  !$omp end parallel
+end program p

flang/test/Lower/OpenMP/Todo/allocate-clause-allocator.f90

@@ -0,0 +1,16 @@
+! REQUIRES: openmp_runtime
+! RUN: %not_todo_cmd %flang_fc1 -emit-llvm -fopenmp -fopenmp-version=51 -o - %s 2>&1 | FileCheck %s
+
+! CHECK: not yet implemented: Unhandled clause allocate in omp.parallel
+! CHECK: LLVM Translation failed for operation: omp.parallel
+program p
+  use omp_lib
+  integer :: x
+  integer :: a
+  integer :: i
+  !$omp parallel private(x) allocate(allocator(omp_default_mem_alloc): x)
+  do i=1,10
+     a = a + i
+  end do
+  !$omp end parallel
+end program p