Issue 12235 & 12236 & 12237 - fix issues around lambda

[Issue 12235](https://d.puremagic.com/issues/show_bug.cgi?id=12235) - ICE on printing mangled name of forward reference lambda by pragma(msg) 
[Issue 12236](https://d.puremagic.com/issues/show_bug.cgi?id=12236) - Inconsistent mangleof result
[Issue 12237](https://d.puremagic.com/issues/show_bug.cgi?id=12237) - Inconsistent behavior of the instantiating enclosing template function