meson: remove obsolete comment about stack frame size

meson: remove obsolete comment about stack frame size

The virStrerror function no longer exists in libvirt so is not a
constraint. At the current stack limit of 4k, and default Linux
stack size of 8 MB, we have a recursion limit of 2048 in the
absolute worst case, and much higher in common case. Even with
smaller stack sizes, we're going to be fine as we don't deeply
recurse in code.

Thus it is not worth spending effort to optimize below our current
4k worst case limit. Removing the comment will stop encouraging
people to spend time on this in future.

Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>