Implement GLX and X functionality through Mesa's EGL interface. This
requires multiple OpenGL contexts and in turn GEM context support in
libdrm/iris, as implemented in libdrm and intel_gpu_drv.
Update recipes and machine.vbox6 files accordingly,
issue #4380
The service is loaded dynamically VBoxSharedClipboard.so at runtime. The
VFS configuration mounts the shared object at /VBoxSharedClipboard.so as
the file is checked by contrib code before loading. An init
configuration in pkg/vbox6/runtime illustrates this and how to re-label
the VBoxSharedClipboard.so ROM to its real name
virtualbox6-sharedclipboard.lib.so.
This is a follow-up commit to "Increase default warning level", which
overrides Genode's new default warning level for targets contained in
higher-level repositories. By explicitly whitelisting all those targets,
we can selectively adjust them to the new strictness over time - by
looking out for 'CC_CXX_WARN_STRICT' in the target description files.
Issue #465
