Make compile without ICE_THREAD_LOCAL_HACK (avoid "Type *TLS = TLS;")

Make compile without ICE_THREAD_LOCAL_HACK (avoid "Type *TLS = TLS;")

Otherwise you get:

In file included from src/IceGlobalContext.cpp:21:
In file included from src/IceCfg.h:21:
src/IceGlobalContext.h:257:44: error: variable 'TLS' is uninitialized when used within its own initialization [-Werror,-Wuninitialized]
    ThreadContext *TLS = ICE_TLS_GET_FIELD(TLS);
                   ~~~                     ^~~
src/IceTLS.h:95:39: note: expanded from macro 'ICE_TLS_GET_FIELD'
                                      ^
So rename the local var to Tls.

BUG=none
R=stichnot@chromium.org

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=3e5009f643a931184cf3437e7204e40c7a61d4d1

[jvoung (off chromium), 2015-03-24 01:19:31]

jvoung@chromium.org changed reviewers:
+ stichnot@chromium.org

[Jim Stichnoth, 2015-03-24 01:34:12]

lgtm

[jvoung (off chromium), 2015-03-24 16:04:18]

Committed patchset #1 (id:1) manually as
3e5009f643a931184cf3437e7204e40c7a61d4d1 (presubmit successful).