* Update the pre-built ICU data files for all platforms

  source/data/in/icudtl.dat for non-Android platforms
  {linux,mac}/icudt*.S for linux/mac
  android/icudtl.dat and android/icudt*.S for Android
  windows/icudt.dll for Windows

* Update Android data trimming script

  1. Make sure that 'default' calendar is kept in locales where it's relevant
    : root, th, fa, ar_SA, etc.
  2. Add a minimal region data to work around a bug in ICU with pool.res
     handling

* Update gn and gyp files
* And add a TODO comment to update.sh to automate the build file update.
* Add it_CH to the locale list.
* Add sr_Latn to unit/reslocal.mk (required by sh) and
  line_normal_fi to brkitr/brklocal.mk (referred to in brkitr/fi.txt) in
  place of line_fi.

* Update and add scripts for data building
* Completely rewrite README.chromium
* Check-in the prebuilt ICU data files/assembly sources for
  Linux,Mac,Windows,Chrome OS and Android.

BUG=575007
TEST=Blink layout tests, webkit unittests
TEST=All bots can build successfully
TEST=net_unittests --gtest_filter="*ilenameUtil*"
TEST=net_unittests --gtest_filter="*IDN*" (pending bug 336973)
TEST=base_unittests --gtest_filter="*Conv*"
TEST=browser_tests --gtest_filter="*ncoding*"
TEST=base_unittests --gtest_filter="*essage*"
TEST=ui_base_unittests --gtest_filter="*ormat*"
TEST=ui_base_unittests --gtest_filter="L10n*"
R=mark@chromium.org

Review URL: https://codereview.chromium.org/1639543006 .

Fix the following errors found by jochen@ in
  https://codereview.chromium.org/960263002/

1. brkitr: en_US_POSIX is not supported. Remove it from brklocal.mk
   : We don't use en_US_POSIX and the remaining dependency on it in
   some unittests was already removed. (we may need it back later,
   though, for breaking an FQDN into components.)
2. coll: Explicitly add id.txt required as the alias/parent of "in" and
   "id_ID". This should not affect the collation in Indonesian locale
   because falling back to the root locale should be fine.
3. lang: Add 'ro_MD.txt' required as the alias of 'mo.txt'.

Also update make_mac_asseymbly.sh to get it to read off the ICU major
version automatically.

Besides, update README.chromium to refer to ICU 54 as done by the
aforementioned CL.

Rebuild the data files and assembly sources (the latter still required
by stand-alone v8 builds) for all the platforms.

icudtl.dll for Windows will be built and checked in in  another CL.

BUG=428145
TEST=Usual ICU update tests before rolling DEPS. See https://codereview.chromium.org/878723002
TBR=jochen@chromium.org

Review URL: https://codereview.chromium.org/962643003

1. Generate and add windows/icudt.dll with the procedure outlined
in README.chromium. It uses a out-of-tree copy of the upstream ICU
along with our custom-built icudtl.dat and a locally modified version
of makedata.mak.

We used to have a separate build/ directory for VS solution/project files
to build icudtl.dll. Maintaining them is rather cumbersom now that we
want to update our ICU (major version changes) more frequently. 

Note that icudt.dll is not used by default (icu_use_data_file_flag=1). 
The GN build still uses it by default and we should not break that build.

2. Add scripts/make_mac_assembly.sh to simplify the generation of the icu
data assembly source file for Mac.

3. Update README.chromium accordingly.

This CL was uploaded and reviewed at 

https://codereview.chromium.org/255943004/

Due to a malfunction at codereview.chromium.org, I'm landing this CL 
manually in two parts. 
This check-in is the 2nd part of the CL dealing with #2 and #3
above.

BUG=132145
TEST=None until icu is rolled to this version.


git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/icu52@266602 4ff67af0-8c30-449e-8e8b-ad334ec8d88c