Improve clog, clog10 handling of values with real or imaginary part slightly above 1 (bug 13629)

[David Miller]

From: Carlos O'Donell <carlos_odonell@mentor.com>
Date: Tue, 7 Aug 2012 10:35:36 -0400

> I don't want to see the testsuite regress at any point in time.

But, it will.

Sparc has regressed for weeks due to some changes in the testsuite
that added checks underflows where prevsiously it did not, and I
haven't had time to investigate further.  It simply happens.