The top-level plugin file gstlibcamera.c is the only C source file in
the whole libcamera GStreamer element. To avoid specifying both C and
C++ compiler arguments in the future, turn it into a C++ file.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>