ui: deprecate use of SDL 1.2 in favour of 2.0 series

The SDL 2.0 release was made in Aug, 2013:

  https://www.libsdl.org/release/

That will soon be 4 + 1/2 years ago, which is enough time to consider
the 2.0 series widely supported.

Thus we deprecate the SDL 1.2 support, which will allow us to delete it
in the last release of 2018. By this time, SDL 2.0 will be more than 5
years old.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20180115142533.24585-1-berrange@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

configure

@@ -5668,6 +5668,12 @@ if test "$gtkabi" = "2.0"; then
     echo "WARNING: future releases. Please switch to using GTK 3.0"
 fi
 
+if test "$sdlabi" = "1.2"; then
+    echo
+    echo "WARNING: Use of SDL 1.2 is deprecated and will be removed in"
+    echo "WARNING: future releases. Please switch to using SDL 2.0"
+fi
+
 if test "$supported_cpu" = "no"; then
     echo
     echo "WARNING: SUPPORT FOR THIS HOST CPU WILL GO AWAY IN FUTURE RELEASES!"

qemu-doc.texi

@@ -2596,6 +2596,13 @@ and 3.x series APIs. Support for the GTK 2.x builds will be
 discontinued, so maintainers should switch to using GTK 3.x,
 which is the default.
 
+@subsection SDL 1.2
+
+Previously QEMU has supported building against both SDL 1.2
+and 2.0 series APIs. Support for the SDL 1.2 builds will be
+discontinued, so maintainers should switch to using SDL 2.0,
+which is the default.
+
 @section System emulator command line arguments
 
 @subsection -tdf (since 1.3.0)

ui/sdl.c

@@ -918,6 +918,9 @@ void sdl_display_init(DisplayState *ds, int full_screen, int no_frame)
             exit(1);
     }
 
+    g_printerr("Running QEMU with SDL 1.2 is deprecated, and will be removed\n"
+               "in a future release. Please switch to SDL 2.0 instead\n");
+
     if (no_frame)
         gui_noframe = 1;