Add a support for newlib

Newlib has _timezone instead of __timezone. pNaCl with newlib needs this change.

BUG=132145
TEST=When rolled, NaCl (with newlib) can be compiled without an error.
R=mark@chromium.org

Review URL: https://codereview.chromium.org/266503003

git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/icu52@267335 4ff67af0-8c30-449e-8e8b-ad334ec8d88c