rabbit_common add support for OTP 22

[vkatsuba]

PR is related to #3307

[michaelklishin]

I'm sorry but we are not interested in adding this kind of complexity. Erlang 22 is no longer supported by RabbitMQ. Those who need to use rabbit_common on Erlang 22 can use an older version.

[michaelklishin]

By the way, pg and pg2 may seem to be almost a drop-in replacement of one another but they are not. pg2 relies on distributed locks and pg is strongly eventually consistent by design. This can matter a great deal. I would not recommend anyone to assume that a macro shim would be safe to use or provide in a library.

[vkatsuba]

@michaelklishin thanks for code review and for providing explanation. Nevertheless it sounds sad, a lot of libraries try to support the last three versions and this means that everyone who uses this library will have to make a choice stop support OTP 22 or not etc. But in any case, many thanks for info.

Regards,
--V

[michaelklishin]

If the choice is between dropping support for 22 or not adopting 24, the answer is obvious: OTP 24 has so much to offer that people will be picking it over OTP 22 any day of the week.