sddm: fix build with Qt 5.15.2+

Close #38078

srcpkgs/sddm/patches/qt-5.15.2.patch

@@ -0,0 +1,23 @@
+From e93bf95c54ad8c2a1604f8d7be05339164b19308 Mon Sep 17 00:00:00 2001
+From: "aacid@kde.org" <aacid@kde.org>
+Date: Thu, 12 Nov 2020 23:42:48 +0100
+Subject: [PATCH] Fix compilation once QTBUG-88431 gets fixed
+
+And also comes closes to Qt6 compatibility
+---
+ src/daemon/XorgDisplayServer.cpp | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/daemon/XorgDisplayServer.cpp b/src/daemon/XorgDisplayServer.cpp
+index 5f93a1b37..d5f29a94a 100644
+--- a/src/daemon/XorgDisplayServer.cpp
++++ b/src/daemon/XorgDisplayServer.cpp
+@@ -65,7 +65,7 @@ namespace SDDM {
+         // create a random hexadecimal number
+         const char *digits = "0123456789abcdef";
+         for (int i = 0; i < 32; ++i)
+-            m_cookie[i] = digits[dis(gen)];
++            m_cookie[i] = QLatin1Char(digits[dis(gen)]);
+     }
+ 
+     XorgDisplayServer::~XorgDisplayServer() {