crypt32/tests: Print a better error if no Verisign root certificates available.

[Juan Lang]

> We have a similar warning already:
> http://source.winehq.org/git/wine.git/?a=blob;f=dlls/ws2_32/tests/sock.c#l2454

That warning is appropriate, because it's testing IPv6, so the warning
applies in all cases.  The reason I'm objecting in this case is that
the warning is printed for any failure, no matter which chain is being
checked, yet this condition can only occur on one of the 15 or so
chains that are checked.  Like I said, I think it's a special case.
--Juan