ParcelFileDescriptor: updates for O_CLOEXEC (API >= Q)

For apps which target Q or above, add the O_CLOEXEC flags to
ParcelFileDescriptors.

O_CLOEXEC is essential for ensuring that file descriptors do not leak
across an exec() boundary. Setting O_CLOEXEC ensures that file
descriptors can't linger around unnecessarily in an exec()ed process
which doesn't use them, making more efficient use of resources.
Additionally, O_CLOEXEC is important in ensuring that untrusted
exec()ed code cannot take advantage of leaked file descriptors.

Test: Android compiles and boots
Bug: 120983106
Change-Id: Idb3eb8f0e43968396a3b3a8bddc26a8d94c55bde