RFR: 8240264: Comment out verbose logging

Wed Apr 8 12:44:14 UTC 2020

On Wed, 8 Apr 2020 08:37:27 GMT, Jose Pereda <jpereda at openjdk.org> wrote:

> This PR comments out too verbose console logging, as it has been done with some other fprintf calls.
> As a follow up of this PR, a custom directive that enables this output if needed can be considered.

@jperedadnr Please change the title of this PR to exactly match the title of the JBS bug. So:
8240264: iOS: Unnecessary logging on every pulse when GL context changes

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PR: https://git.openjdk.java.net/jfx/pull/165