reduce icu data library size

[springmeyer]

There are working hacks around (http://src.chromium.org/svn/trunk/deps/third_party/icu42/patches/data.build.patch) that reduce the size for old icu versions. And there are out of date/irrelevant docs at http://userguide.icu-project.org/icudata#TOC-Reducing-the-Size-of-ICU-s-Data:-Conversion-Tables

Need to figure out if anyone has actually pulled this off.

[springmeyer]

Looks like to even trigger the data library to be regenerated (a precursor to actually making it smaller) you need to delete the bundled one at `rm -rf ./data/in/*dat.

But this does not work because then the clearly out of data build system borks:

make[1]: *** No rule to make target `mappings/convrtrs.txt', needed by `out/build/icudt51l/cnvalias.icu'.  Stop.
make[1]: *** Waiting for unfinished jobs....

[springmeyer]

some notes on how small it can get (4 MB without any data): http://qt-project.org/groups/qt-contributors-summit-2013/wiki/pdf/Qt_ICU | http://comments.gmane.org/gmane.comp.lib.qt.devel/12244

[springmeyer]

http://apps.icu-project.org/datacustom/