Bugfix - commenting-out unused member which results in build error on OS X with latest Xcode.

- Build error due to -Werror,-Wunused-private-field clang args.
- Raised with gtest group (as it also occurs with latest gtest:master but for a different
  variable) with patch, but they don't want to fix for compatibility with legacy compilers/OS
  see here: https://groups.google.com/forum/?fromgroups=#!topic/googletestframework/S1KLl2jkzws

Change-Id: I99984bcd9d07f6eb0e3fac58e27ddf0ac9e54265

internal/ceres/gmock_gtest_all.cc

diff --git a/internal/ceres/gmock_gtest_all.cc b/internal/ceres/gmock_gtest_all.cc
index f7ead68..15ae355 100644
--- a/internal/ceres/gmock_gtest_all.cc
+++ b/internal/ceres/gmock_gtest_all.cc
@@ -601,7 +601,9 @@
   bool list_tests_;
   String output_;
   bool print_time_;
-  bool pretty_;
+  // TODO(keir): We removed this to fix the unused private variable issue;
+  // remove this when/if upstream has the patch.
+  //bool pretty_;
   internal::Int32 random_seed_;
   internal::Int32 repeat_;
   bool shuffle_;