handle storage exceptions when trying to set mtime
handle storage exceptions when trying to set mtime

not all storage backends can handle setting the mtime and they might
not always handle that error correctly.

Signed-off-by: Robin Appelman <474ee9ee179b0ecf0bc27408079a0b15eda4c99d@icewind.nl>

nextcloud/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,nextcloud/server,andreas-p/nextcloud-server