CA-145257: Set the right month for host_crashdump.

Date.of_float increments tm_mon by 1.So, we need to pass tm_mon value
decremented by 1.

Signed-off-by: Ravi Pandey <ravi.pandey@citrix.com>
Merge pull request #1927 from johnelse/ca-145257-master

CA-145257: Set the right month for host_crashdump.