Set GDK_BACKEND=x11 to prevent crashes on Wayland

See https://bugzilla.redhat.com/show_bug.cgi?id=1661324
and https://trac.wxwidgets.org/ticket/17702
and https://github.com/slic3r/Slic3r/pull/4650

slic3r-wayland.patch

@@ -0,0 +1,12 @@
+diff --git a/slic3r.pl b/slic3r.pl
+index 80e6dc7..36d331d 100755
+--- a/slic3r.pl
++++ b/slic3r.pl
+@@ -20,6 +20,7 @@ use Time::HiRes qw(gettimeofday tv_interval);
+ $|++;
+ binmode STDOUT, ':utf8';
+ binmode STDERR, ':utf8';
++$ENV{GDK_BACKEND} = 'x11';
+ 
+ our %opt = ();
+ my %cli_options = ();

slic3r.spec

@@ -5,7 +5,7 @@
 
 Name:           slic3r
 Version:        1.3.0
-Release:        4%{?dist}
+Release:        5%{?dist}
 Summary:        G-code generator for 3D printers (RepRap, Makerbot, Ultimaker etc.)
 License:        AGPLv3 and CC-BY
 # Images are CC-BY, code is AGPLv3
@@ -22,6 +22,7 @@ Patch2:         %{name}-english-locale.patch
 Patch3:         %{name}-linker.patch
 Patch4:         %{name}-clipper.patch
 Patch5:         %{name}-1.3.0-fixtest.patch
+Patch6:         %{name}-wayland.patch
 
 Source1:        %{name}.desktop
 Source2:        %{name}.appdata.xml
@@ -117,6 +118,7 @@ for more information.
 %patch4 -p1
 %endif
 %patch5 -p1 -b .fixtest
+%patch6 -p1
 
 # Optional removals
 %if %{use_system_admesh}
@@ -232,6 +234,9 @@ SLIC3R_NO_AUTO=1 perl Build.PL installdirs=vendor
 %{_datadir}/%{name}
 
 %changelog
+* Sat Dec 22 2018 Miro Hrončok <mhroncok@redhat.com> - 1.3.0-5
+- Set GDK_BACKEND=x11 to prevent crashes on Wayland (#1661324)
+
 * Sat Jul 14 2018 Fedora Release Engineering <releng@fedoraproject.org> - 1.3.0-4
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_29_Mass_Rebuild