renderer-native: Fix memory leak in secondary GPU update

Leaking a texture object and a framebuffer object every time you update
the secondary GPU is perhaps not the best plan.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/1011


(cherry picked from commit 545fcb3dbf)

src/backends/native/meta-renderer-native-gles3.c

@@ -82,6 +82,9 @@ paint_egl_image (MetaGles3   *gles3,
                                     0, 0, width, height,
                                     GL_COLOR_BUFFER_BIT,
                                     GL_NEAREST));
+
+  GLBAS (gles3, glDeleteTextures, (1, &texture));
+  GLBAS (gles3, glDeleteFramebuffers, (1, &framebuffer));
 }
 
 gboolean