[libgomp, testsuite] Reduce recursion depth in declare_target-*.f90

[libgomp, testsuite] Reduce recursion depth in declare_target-*.f90

When running the libgomp testsuite with GOMP_NVPTX_JIT=-O0 using an nvptx
accelerator (Nvidia T400, 2GB), I run into:
...
libgomp: cuCtxSynchronize error: unspecified launch failure \
  (perhaps abort was called)

libgomp: cuMemFree_v2 error: unspecified launch failure

libgomp: device finalization failed
FAIL: libgomp.fortran/examples-4/declare_target-1.f90   -O0  execution test
...

The test-case contains:
...
  ! Reduced from 25 to 23, otherwise execution runs out of thread stack on
  ! Nvidia Titan V.
  if (fib (23) /= fib_wrapper (23)) stop 2
...

Fix this by reducing the fib/fib_wrapper argument from 23 to 22.

Same for declare_target-2.f90.

Tested on x86_64 with nvptx accelerator.

libgomp/ChangeLog:

2022-01-27  Tom de Vries  <tdevries@suse.de>

	* testsuite/libgomp.fortran/examples-4/declare_target-1.f90: Reduce
	recursion depth.
	* testsuite/libgomp.fortran/examples-4/declare_target-2.f90: Same.