RFR: 8320965: Scrolling on a touch enabled display fails on Wayland [v2]

[Jose Pereda]

> This PR replaces the deprecated `gdk_pointer_grab` with `gdk_seat_grab`, and `gdk_pointer_ungrab ` with `gdk_seat_ungrab`, using runtime checks and wrapped functions for GTK 3.20+ (so systems without it still run with GTK 3.8+), and fixes the dragging issue on Wayland.

Jose Pereda has updated the pull request incrementally with one additional commit since the last revision:

  remove compile-time if checks

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1305/files
  - new: https://git.openjdk.org/jfx/pull/1305/files/f498b835..99230ca6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1305&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1305&range=00-01

  Stats: 32 lines in 3 files changed: 5 ins; 8 del; 19 mod
  Patch: https://git.openjdk.org/jfx/pull/1305.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1305/head:pull/1305

PR: https://git.openjdk.org/jfx/pull/1305