1. Apply post-56 patches from the trunk for measure/date format
    http://bugs.icu-project.org/trac/ticket/11986
    http://bugs.icu-project.org/trac/ticket/12031
    http://bugs.icu-project.org/trac/ticket/12030
    http://bugs.icu-project.org/trac/ticket/12041
2. Generate a combined patch (measure_format.patch) for the above.
3. Split locale_google.patch into 'locale_google.patch' and
   'relative_date.patch'. The latter is taken from Android.
4. Update README.chromium

Besides, apply two local patches : {tzdetect,xlit..}.patch and
adjust gb18030.ucm and the corresponding patch

Also, remove obsolte patches and update README.chromium

BUG=575007
R=mark@chromium.org

Review URL: https://codereview.chromium.org/1621943002 .