libcamera: Move file_descriptor.h to base/

The FileDescriptor class is a generic helper that matches the criteria
for the base library. Move it there.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/v4l2_videodevice.cpp

@@ -22,11 +22,10 @@
 #include <linux/version.h>
 
 #include <libcamera/base/event_notifier.h>
+#include <libcamera/base/file_descriptor.h>
 #include <libcamera/base/log.h>
 #include <libcamera/base/utils.h>
 
-#include <libcamera/file_descriptor.h>
-
 #include "libcamera/internal/formats.h"
 #include "libcamera/internal/framebuffer.h"
 #include "libcamera/internal/media_device.h"