using HUP and INT signals to the rotatelogs process.

This is helpful, when log activity is low, but you want
rotatelogs to close the open log files.

SIGHUP triggers checking the rules given during startup,
SIGINT forces rotate independently form those rules.

When the signal triggers a rotation, the open file
is closed immediately. The new file is opened when
new log data arrives, or in case "-f" was given it
is opened immediately.

Based on my patch in BZ 44427.

Note on Windows: The new functionality is undefined when
SIGHUP or SIGINT are not available. Does the use case
make sense on Windows? If so, which signals should we use?


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@733493 13f79535-47bb-0310-9956-ffa450edef68