[OpenMP][DeviceRTL] Fix the support for tasking on the device

This patch fixes the support for tasking on the device.

Note: AMDGPU doesn't support it yet because of no support for `malloc` and `free`.

Fix #59946.

```
➜  ./test_parallel_master_device
[OMPVV_RESULT: test_parallel_master_device.c] Test passed on the device.
```

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D141562