(Previous patch set was reverted due to issue with priv_stack.
Resubmitting after fixing the faults caused by priv_stack.noinit
not at the end of RAM.)
This adds a linker flag and necessary changes to linker scripts
so that linker will warn about orphan sections.
Relates to #5534.
Fixes#10473, #10474, #10515.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>