[sv-ec] handling of static random variables (mantis #1416)

I believe we talked about static random variables in the
last conference call.  I have entered mantis #1416 along
with a proposal to clarify this issue.

The proposal clarifies that the rand_mode state of
a static random variable is also static - changing 
rand_mode in any instance changes rand_mode in all.

Also if a randc variable is static, the associated 
state is also static - one sequence of unique values
for all instances.

- Ray