Lint cleanup from Jim Roseborough.

Change-Id: I6ddbf5c3d66595d27f7967a309768e5f5dd7e1fd
diff --git a/internal/ceres/corrector.cc b/internal/ceres/corrector.cc
index cbf49ec..f9deb87 100644
--- a/internal/ceres/corrector.cc
+++ b/internal/ceres/corrector.cc
@@ -85,7 +85,7 @@
   }
 
   // We now require that the first derivative of the loss function be
-  // positive only if the second derivative is non-zero. This is
+  // positive only if the second derivative is positive. This is
   // because when the second derivative is non-positive, we do not use
   // the second order correction suggested by BANS and instead use a
   // simpler first order strategy which does not use a division by the