Make sure Layout doesn't modify the paint

Previously, Layout would modify the HyphenEdit of the Paint passed to it
for its internal operations, potentially leaving the Paint in a different status than when
it was created. Now we use an internal copy of the Paint to modify.

Fixes: 64452136
Test: bit CtsTextTestCases:android.text.cts.
Test: bit FrameworksCoreTests:android.text.
Change-Id: I0b95a10c05711350950d6c8d6501f6af9414d413