imfile - proposed fix for file handle leaks

[n2yen]

• FIle handler leaks can occur if the deleted file still has a lingering symbolic link (pointing to it). Reason is, even if the file has actually been deleted, fstat will return successfully, and thus this block never gets a chance to release the file handle.

[n2yen]

hi @rgerhards ,
Wonder if this is one of the possible edge cases discussed:

rsyslog/plugins/imfile/imfile.c

Lines 840 to 842 in 4c11c58

	TODO: check the full implications, there are for sure some!
	e.g. file has been closed, so we will never have old inode (but
	why was it closed then? --> check)

mind having a look when you get a chance? thank you!