RFR: 8245635: GlassPasteboard::getUTFs fails on iOS

[Jose Pereda]

As a follow-up of JDK-8245456, IosPasteboard throws a ClassCastException when trying to paste clipboard content on iOS
devices. Same fix apply, using the correct signature.

When retrieving the UTF formats, the native method fails to create the correct String array, as the total number of
keys is not taken into account. Using a for loop fixes the issue.

Relates to JDK-8245499 and JDK-8245575

-------------

Commit messages:
 - Fill keys array with for loop
 - Use correct array type signature

Changes: https://git.openjdk.java.net/jfx/pull/233/files
 Webrev: https://webrevs.openjdk.java.net/jfx/233/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8245635
  Stats: 11 lines in 1 file changed: 4 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/jfx/pull/233.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/233/head:pull/233

PR: https://git.openjdk.java.net/jfx/pull/233