This is so when a debugger attaches using MPIR, it can step out of this stack back into main.
This cannot be done with certain aggressive optimisations and missing debug information.
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Jeff Squyres <jsquyres@cisco.com>
Co-authored-by: Jeff Squyres <jsquyres@cisco.com>
(cherry-picked from 20f5840)