postgres-lambda-diff

Subject: [HACKERS] backend/optimizer/geqo/geqo_erx.c

I sent these changes in with a bunch of others.  Some were folded in but
others, like these, were not.  I am not sure why so I am resending this
to the developers list by itself for discussion.

The readon why I suggest these changes is that the compiler can't tell
that minimum_count is initialized before it is used.  The tests that I
add in here will cause an immediate error if it doesn't.  As the comments
below suggest, if it is 100% guaranteed that the variable will always
be initialized then how this is so should be commented here.  I don't
know how much strain the actual test puts on the performance but if it
isn't too much then maybe leave it in for absolute safety anyway.

There are also a few returns just to stop warnings.