When using the EGLStream backend, the MetaRendererNative passed a
GClosure to KMS when using EGLStreams, but KMS flip callback event
handler in meta-gpu-kms.c expected a closure wrapped in a closure
container, meaning it'd instead crash when using EGLStreams. Make the
flip handler get what it expects also when using EGLStreams by wrapping
the flip closure in the container before handing it over to EGL.
https://bugzilla.gnome.org/show_bug.cgi?id=790316
When drmHandleEvent() returns an error and errno is set to EAGAIN,
instead of ending up in a busy loop, poll() the fd until there is
anything to read.
https://bugzilla.gnome.org/show_bug.cgi?id=785381
In order to eventually support multilpe GPUs with their own connectors,
split out related meta data management (i.e. outputs, CRTCs and CRTC
modes) into a new MetaGpu GObject.
The Xrandr backend always assumes there is always only a single "GPU" as
the GPU is abstracted by the X server; only the native backend (aside
from the test backend) will eventually see more than one GPU.
The Xrandr backend still moves some management to MetaGpuXrandr, in
order to behave more similarly to the KMS counterparts.
https://bugzilla.gnome.org/show_bug.cgi?id=785381
