I recently saw that gfortran does not support derived type components
with 'target update', an OpenMP 5.0 feature.

When adding it, I also found out that strides where not handled. There
is probably some room of improvement about what to copy and what not,
but copying too much should be fine.

Build + (reg)tested on x86_64-gnu-linux without offloading configured
+ libgomp tested on x86_64-gnu-linux with nvptx offloading.
OK for mainline?

  * * *

PS: Follow-up work items:
* Strides: OpenMP seemingly permits also 'a%b([1,6,19,12])' as
   long as the first index has the lowest address. – And also
   'a%b(:)%c' is permitted – both not handled in this patch
   (and rejected with a compile-time error)
* There seems to be some problems with 'alloc' with pointers
   and allocatables in components – but I have not rechecked.
* For allocatables, 'target update' needs to do a deep mapping;
   I need to check whether that's the case.
Note for the last two: allocatable components only works OG11/OG12
and I urgently need to cleanup + (re)submit that patch to mainline.
(It came too late for GCC 12.)

* There might be also some issue mapping/refcounting, which I have not
   investigated - affecting the 'target exit data' of target-11.f90.

PPS: I intent to file at least one/some PRs about those issues, unless
I can fix them quickly.
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