IMPALA-3230: Spurious errors from DeleteOldLogs()
IMPALA-3230: Spurious errors from DeleteOldLogs()

DeleteOldLogs() uses glob to locate log files matching a given path.
When glob returns an error, we log it, but since glob returns an error
when no matching files are found, and since its common to have no
matching files, eg. for uncommon logging levels like FATAL, this
results in a significant amount of error logging for something that
is not really an error.

This patch updates DeleteOldLogs() to simply return when no matching
log files are found.

Change-Id: I485b7c97b01bf17ad75cf8a456b2e4fbce91d31d
Reviewed-on: http://gerrit.cloudera.org:8080/2596
Reviewed-by: Dan Hecht <20ebd99959f0f6e5dcb0fc319b4d8ef53a16b5fb@cloudera.com>
Tested-by: Internal Jenkins

kapilrastogi/Impala,kapilrastogi/Impala,kapilrastogi/Impala,kapilrastogi/Impala,kapilrastogi/Impala,kapilrastogi/Impala,kapilrastogi/Impala