Default icu data file for all architectures was set to icudtl.dat, for
big endian this should be icudtb.dat. This will fix intl tests for big
endian once v8 rolls to a newer version of icu that supports big endian.

BUG=
TEST=intl/*

Review-Url: https://codereview.chromium.org/2182043002
Cr-Commit-Position: refs/heads/master@{#38102}