RFR: 8217955: Problems with touch input and JavaFX 11

[Jose Pereda]

This PR filters out `GDK_TOUCH_EVENT_MASK` from `GDK_ALL_EVENTS_MASK` to prevent touch events from being used instead of regular mouse events on Linux platforms. Note that the touch events will be delivered as mouse pressed/dragged events.

Since we still compile with GTK 2.x the bit flag (that was introduced in GTK 3.4) needs to be defined.

This PR has been tested on Ubuntu 20.04 with a touch enabled display.

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Commit messages:
 - Filter out GDK_TOUCH_MASK events

Changes: https://git.openjdk.java.net/jfx/pull/457/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=457&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8217955
  Stats: 15 lines in 3 files changed: 10 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jfx/pull/457.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/457/head:pull/457

PR: https://git.openjdk.java.net/jfx/pull/457