src/update_handler: add fsync call to copy_raw_image()
src/update_handler: add fsync call to copy_raw_image()

This assures the content is fully written to disk before exiting.

This works for GUnixOutputStream only, but it is a safe assumption to
always have one on a Linux system.

Signed-off-by: Jim Brennan <17a316de37f50911ce1eeb191efe7503950e1749@impinj.com>
Signed-off-by: Enrico Joerns <a2e5f936c390f36494e46e71bcfbe365bb1e8c49@pengutronix.de>

rauc/rauc,jluebbe/rauc,jluebbe/rauc,ejoerns/rauc,rauc/rauc,rauc/rauc,ejoerns/rauc,ejoerns/rauc,jluebbe/rauc