ui: use libexpoxy

libepoxy does the opengl extension handling for us.

It also is helpful for trouble-shooting as it prints nice error messages
instead of silently failing or segfaulting in case we do something
wrong, like using gl commands not supported by the current context.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

configure

@@ -3166,14 +3166,14 @@ else
 fi
 
 if test "$opengl" != "no" ; then
-  opengl_pkgs="gl glesv2"
+  opengl_pkgs="gl glesv2 epoxy"
   if $pkg_config $opengl_pkgs x11 && test "$have_glx" = "yes"; then
     opengl_cflags="$($pkg_config --cflags $opengl_pkgs) $x11_cflags"
     opengl_libs="$($pkg_config --libs $opengl_pkgs) $x11_libs"
     opengl=yes
   else
     if test "$opengl" = "yes" ; then
-      feature_not_found "opengl" "Install GL devel (e.g. MESA)"
+      feature_not_found "opengl" "Please install opengl (mesa) devel pkgs: $opengl_pkgs"
     fi
     opengl_cflags=""
     opengl_libs=""

include/ui/console.h

@@ -10,8 +10,7 @@
 #include "qapi/error.h"
 
 #ifdef CONFIG_OPENGL
-# include <GLES2/gl2.h>
-# include <GLES2/gl2ext.h>
+# include <epoxy/gl.h>
 #endif
 
 /* keyboard/mouse support */

include/ui/shader.h

@@ -1,7 +1,4 @@
-#ifdef CONFIG_OPENGL
-# include <GLES2/gl2.h>
-# include <GLES2/gl2ext.h>
-#endif
+#include <epoxy/gl.h>
 
 void qemu_gl_run_texture_blit(GLint texture_blit_prog);