Explicitly set Java language version when building ICU4J in Android.

For backward compatibility the ICU4J build configuration uses an older
Java language version than Android does by default, which in the past
has led to people accidentally submitting changes that wouldn't build
using ICU4J's "ant check":

https://android.googlesource.com/platform/external/icu/+/6ba7821
https://android.googlesource.com/platform/external/icu/+/137142e

Test: mmma libcore external/icu
Test: CtsIcuTestCases
Test: CtsLibcoreTestCases
Change-Id: I0c8cfeed788093428745c6f1318884899e3e9b00
1 file changed