foundation: The "lastSync" member in TimeSync.java had multiple meanings....

foundation: The "lastSync" member in TimeSync.java had multiple meanings. Consequently, this commit splits it into two variables.

If the resync() operation failed, the TimeSync thread tried to re-execute resync() every sleep interval (50ms) by default.

In consequence, the OSD log file filled up with these entries:

[ I | DIRClient            | TSync Thr       |  26 | Jun 27 12:21:24 ] Request failed due to exception: java.io.IOException: sending RPC failed: reconnecting to the server 'xxx/172.24.100.4:32638' was blocked locally to avoid flooding
[ I | DIRClient            | TSync Thr       |  26 | Jun 27 12:21:24 ] Request failed due to exception: java.io.IOException: sending RPC failed: reconnecting to the server 'xxx/172.24.100.4:32638' was blocked locally to avoid flooding

This commit introduces a new member lastSyncAttempt. From now on, the next should be executed only after "remote_time_sync" milliseconds elapsed.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@3199 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534