fragments/qemu: add support for enabling sdl in qemu

This has been the default in poky's local.conf template for
a long time, but it's not enabled directly in poky distro.
To allow better sstate reuse and a better user experience
on a typical laptop (qemu will pop up a graphical window directly),
let's add this fragment and enable it in official bitbake-setup
configurations.

(From OE-Core rev: fad31afcd12d5724c5ba32240cfc6404fe127ecd)

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/conf/fragments/qemu/enable-native-sdl.conf

@@ -0,0 +1,8 @@
+BB_CONF_FRAGMENT_SUMMARY = "Enable SDL support for direct graphical output on the build host."
+BB_CONF_FRAGMENT_DESCRIPTION = "By default qemu is built with a internal VNC server \
+support. To see graphical output from the guest system, one can use a VNC client to \
+connect to it. This fragment enables Simple Directmedia Layer support, which allows \
+seeing the graphical output from guest directly in a X/Wayland session on the build host machine. \
+"
+
+PACKAGECONFIG:append:pn-qemu-system-native = " sdl"