input-settings/x11: Add missing clutter_x11_trap_x_errors around XIGetProperty
Add missing clutter_x11_[un]trap_x_errors around the XIGetProperty call in meta-input-settings-x11.c's get_property helper function.
This fixes mutter crashing with the following error if the XInput device goes away at an inconvenient time:
X Error of failed request: XI_BadDevice (invalid Device parameter)
Major opcode of failed request: 131 (XInputExtension)
Minor opcode of failed request: 59 ()
Device id in failed request: 0x200011
Serial number of failed request: 454
Current serial number in output stream: 454
Note this fix really should also be added to the gnome-3-34 branch (where it applies cleanly).