The problem is that there are so many variables:
* which version of which compiler
* optimization flags
* which version of gdb
* which CPU architecture
etc (and the compiler and/or gdb could be carrying patches from downstream distributors...)

All of these can affect the debugging experience; as soon as optimizations are turned on it's very hard to predict exactly how well we can capture the frame information in the debugger.

Hence it makes sense to skip these tests for optimized builds, to avoid creating noise in the buildbots.

Downstream distributions might want to re-enable the tests, if they have sufficient control over the compiler and debugger versions that are in use, I guess.

Or maybe there's a way to express some of the above sanely?  Not sure.

Hope this is constructive.