check osdp close file status (according prototype function comments)

[sgouraud]

could be usefull if any error during file closing

[sidcha]

I conciously chose to ignore this error, here is my reasoning:

• this close failure is a local issue, the OSDP peer does not need to know about it.
• all bytes of the file has been sent to the peer and the peer has probably closed it's FD already so don't make sense to ask it to discard the contents due to this issue.

On the other hand, we can have the log message. What do you think?

[sgouraud]

File closing error should significate data corruption on PD, which could need a full file data transfert again . By the way, I don't see any error on osdp_FTSTAT reply which should explain this file's closing error back to ACU :
-1= abort file transfer
-2= unrecognized file contents
-3=f ile data unacceptable (malformed)

If you think this error could be ignore, the comments above should be remove : https://github.com/goToMain/libosdp/blob/master/include/osdp.h#L1093

[sidcha]

Reasoning sounds good to me. Thanks for the PR.