xmlsecurity OOXML export: don't attempt to sign other signatures

For one, MSO doesn't do that either by default.

For another, this would currently result in a io::IOException, because:

- the root storage is opened read-write, to be able to add the signature
- then _xmlsignatures/newsig is opened read-write to be able to write
the signature
- opening _xmlsignatures/something as read-only still opens the
_xmlsignatures storage as read-write -> boom, we tried to open the
same sub-storage read-write two times, OStorage::openStorageElement()
detects that

Change-Id: I2b90dc044bcfb835df4f19a339a0447e69f42975

0 files changed, 0 insertions, 0 deletions