In the case of partially mapped structs, libomptarget sometimes adds padding to device allocations to ensure they are aligned properly. However, without this patch, it considers that padding to be mapped to the host, which can cause array extension errors when other parts of the struct are separately mapped. This patch keeps the padding but treats it as unmapped. See the new test case for an example.

In the case of partially mapped structs, libomptarget sometimes adds padding to device allocations to ensure they are aligned properly. However, without this patch, it considers that padding to be mapped to the host, which can cause presence checks (e.g., `omp_target_is_present` or a `present` modifier) to misbehave for unmapped parts of the struct. This patch keeps the padding but treats it as unmapped. See the new test case for examples.

In the case of partially mapped structs, libomptarget sometimes adds padding to device allocations to ensure they are aligned properly. However, without this patch, it considers that padding to be mapped to the host, which can cause array extension errors when other parts ofpresence checks (e.g., the struct are separately mapped. This patch keeps the padding but`omp_target_is_present` or a `present` modifier) to misbehave for unmapped parts of the struct. This patch keeps the padding but treats it as unmapped. See the new test case for an examples.