Fix trim_data.sh to delete empty currency blocks

After data trimming, data/curr/en_GB.txt has empty "Currencies" block.
This prevents a locale fallback chain from being triggered for currency
symbols (en-GB => en-001 => en), leading all the currency symbols in en-GB
to be the last resort value (ISO 3-letter currency code). To avoid that,
trim_data.sh is revised to drop empty "Currencies" block entirely ('Missing'
triggers a fallback chain, but 'empty' goes straight to the last resort.)

Additional currency data fixes:

1. Serbian: RON and ROL display names are swapped. RON is the current
currency and should be included with a shorter display name.

2. Add a few more en-* locale variants to the locale list for currency.

Moreover, make_data_all.sh is updated to work wherever the Chromium
source tree is.

Finally, update the list of resources to remove from cast's ICU data
and rebuild it with ICU 60.  Added entries to cast-removed-resources.txt
are data for locale-variants that are not useful in Cast.

Bug: 791318
Test: See the bug
Change-Id: Ib09ee36e3447557636d60d8aeabc7ca047718236
Reviewed-on: https://chromium-review.googlesource.com/810099


Reviewed-by: Mark Mentovai <mark@chromium.org>