boost/log: format_named_scope can not handle the function with anonymous namespace

[Arlea1221]

use boost::log::format_named_scope, it can not handle the function with anonymous namespace:
%n (%f:%l) : void aa::bb::{anonymous}::test() (/home/joycguan/projects/test/62_log.cpp:443)
--> Right
%c (%f:%l) : anonymous}::test (/home/joycguan/projects/test/62_log.cpp:443)
--> Wrong

[Lastique]

%c and %C placeholders are known to not support all cases well. Do not use them if you want predictable output.