r24701: Fix the swat build

r24701: Fix the swat build

Swat has not been built by default for a while, so I did not notice that
the _ macro is actually used. Re-add the lang_msg_rotate function, this
time only to swat so that this is the only binary that has to take the
16k penalty.
(This used to be commit 191e1ef840c293f8575cc0a3f3ffba2080431fae)