package/x11r7/xserver_xorg-server: Add patch to fix v1.19.1 with SIGIO

package/x11r7/xserver_xorg-server: Add patch to fix v1.19.1 with SIGIO

The commit 6a5a4e60373c from xserver v1.19.1 removes SIGIO support for
input [1].

The current patch coming from Open Embedded [2] removes a check of
'useSIGIO'. This check was producing a segfault error while using
X11 and Vivante driver [3]. Thanks to Gary Bisson to point out this
patch!

[1] https://cgit.freedesktop.org/xorg/xserver/commit/?id=6a5a4e60373c1386b311b2a8bb666c32d68a9d99
[2] https://patchwork.openembedded.org/patch/136696/
[3] http://lists.busybox.net/pipermail/buildroot/2017-February/183994.html

Signed-off-by: Mylène Josserand <mylene.josserand@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>