Signal no region descriptors follow the ETH table.

In our implementation, the 2-word EXIDX is directly followed
by a 3-word ETH for personality 2 unwind interpretter.
According to ARM EHABI 9.2, "region of interest" descriptors
should follow, finished by a single zero word.
As the generated functions don't have any such regions,
only the closing zero needs to be present.

Change-Id: I65fde548371cf12a31aac3e8829275965e034f3a
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>