Is MySQL Community Server 5.7.11 compatible with SLES 11 SP3?
Nobody guarantees their software. The GPL doesn't and neither do the commercial companies - the IT industry is notorious for not actually guaranteeing their work as being fit for purpose in any way and indemnifying themselves against any damages that could be caused. 

This is even though they're actually paid for software - at least the GPL doesn't charge money. To clarify, they can, but generally don't. For example, MySQL is available under the GPL and a commercial licence.


If you compile it yourself, you're on your own. 
If you download community binaries you're on your own. 
If you pay, you're pretty much on your own. What you're really paying for is support and monitoring/backup tools which are not available under the GPL.


Finally, and perhaps to put you at ease (and even answer the question :-) ), if you can compile it, it works. I've compiled many versions of MySQL, MariaDB and Percona Server (it's my preferred way of installing - multiple servers on the same machine are a piece of cake) and I've never had a problem with buggy software (apart from the car-wreck that is MySQL that is! :-) ).

Compiling an old version on a new OS will work - the reverse may not be, but I've never done that.