Use pkg-config to find the prefix for X11 install

Needed to run the XKB extension where we used to expect X11 to be
installed in /usr. In FreeBSD, for instance, X11 is installed in
/usr/local like all the other not out-of-the-box packages.

Same thing goes for the compose platform input context plugin.

Change-Id: Ib7ace3117eaacc6e150394450d1330cba654ba8a
Reviewed-by: Gatis Paeglis <gatis.paeglis@digia.com>
Fix eglfs compilation on raspi

For some reason the Raspberry Pi hook includes qeglfscursor.h even
though it is not necessary. Remove this because the file got moved to
eglconvenience.

Change-Id: Ia65f5a8366d750f93eacee49004219e664b52af2
Reviewed-by: Andy Nichols <andy.nichols@digia.com>
xcb: Do not leak when compressing events

The event must be freed in all cases, also when a motion or configure
notify is skipped.

Change-Id: Ie55e62d0c3ab25bd9b20cc85098ea337d0b1ac5d
Reviewed-by: Uli Schlachter <psychon@znc.in>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>