RFR: 8260245: Update ICU4C to version 68.2

[Kevin Rushforth]

On Mon, 5 Apr 2021 18:14:36 GMT, Arun Joseph <ajoseph at openjdk.org> wrote:

> We currently use ICU4C version 64.2. We should update to the latest stable version 68.2.
> http://site.icu-project.org/home

I did a review of all change not in the ThirdParty/icu. All looks good to me. There is one more instance of the hard-coded `68.2` that could be defined as a property.

I've done sanity testing on Windows and and Mac. No problems that I can see. I'll do a bit more testing.

build.gradle line 3383:

> 3381:     dependencies {
> 3382:         if (IS_COMPILE_WEBKIT) {
> 3383:             icu name: "icu4c-68.2-data-bin-l", ext: "zip"

I think the `68.2` could also be a property.

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PR: https://git.openjdk.java.net/jfx/pull/456