improvements in example-msg-generator

[nobles]

In this patch I added two changes to example-msg-generator. With these changes, example-msg-generator can be used for testing purposes easier.

• First message is sent immediately: we do not need to wait freq. With this, the tests can speed up.
• With the new num option, users can limit how many messages should be generated. Zero means infinite messages (this is the default). Positive integer means the maximum number of messages.

Example:

source { example-msg-generator(freq(1) num(5)); };

[kira-syslogng]

This user does not have permission to start the build. Can one of the admins verify this patch and start the build?
(admin: you have the next options (make sure you checked the code):
"ok to test" to accept this pull request (and further changes) for testing
"test this please" for a one time test run
do nothing -> CI won't start)

[kira-syslogng]

This user does not have permission to start the build. Can one of the admins verify this patch and start the build?
(admin: you have the next options (make sure you checked the code):
"ok to test" to accept this pull request (and further changes) for testing
"test this please" for a one time test run
do nothing -> CI won't start)

[furiel]

@kira-syslogng ok to test

[Kokan]

Would you consider changing the num behavior where there is no way to configure msg generator not to send messages (num(0)). I would define num(0) as infinite number of messages, and use that as a default value. (negative number to produce infinite number of messages would be fine)

Using zero as infinite in configuration not so uncommon.

[kira-syslogng]

Build SUCCESS

[kira-syslogng]

Build SUCCESS

[gaborznagy]

Thank you for the contribution!