qemu: Work around the crash seen on Ubuntu.

Due to different stack contents in sdl_display_init on Ubuntu vs other distros,
an uninitialized structure is causing a crash.  Zeroing the structure makes the
behavior uniform across distros, avoiding the Ubuntu crash, but doesn't fix the
underlying bugs, notably:
the return value of SDL_GetWMInfo needs to be checked, as it's currently
failing silently
the underlying reason for the failure of SDL_GetWMInfo needs to be found -
there is a GetWMINfo method in the internal SDL structure which is NULL, and
the reason for this needs to be found.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>

meta/packages/qemu/qemu-0.12.4/init-info.patch

@@ -0,0 +1,16 @@
+# This is a workaround to the crashes seen on Ubuntu.  Setting info to zero
+# makes info.info.x11.display zero and avoids the calls to
+# opengl_exec_set_parent_window, one of which is crashing.
+
+Index: qemu-0.12.4/sdl.c
+===================================================================
+--- qemu-0.12.4.orig/sdl.c
++++ qemu-0.12.4/sdl.c
+@@ -871,6 +871,7 @@ void sdl_display_init(DisplayState *ds, 
+     vi = SDL_GetVideoInfo();
+     host_format = *(vi->vfmt);
+ 
++    bzero(&info, sizeof(info));
+     SDL_GetWMInfo(&info);
+     if (info.subsystem == SDL_SYSWM_X11 && info.info.x11.display)
+         opengl_exec_set_parent_window(info.info.x11.display,

meta/packages/qemu/qemu_0.12.4.bb

@@ -14,5 +14,6 @@ SRC_URI = "\
     file://fix-nogl.patch \
     file://qemugl-allow-glxcontext-release.patch \
     file://linker-flags.patch"
+    file://init-info.patch;patch=1"
 
 S = "${WORKDIR}/qemu-${PV}"