fix Issue 12235 - ICE on printing mangled name of forward reference lambda by pragma(msg)
fix Issue 12236 - Inconsistent mangleof result
fix Issue 12237 - Inconsistent behavior of the instantiating enclosing template function
Normalize mangling scheme

- Don't encode return type and inferred attributes on parents part.
  * Voldemort type issue is properly solved.
  * The mangled name of function-local symbol is independent from the enclosing function inference.
- Specially mangle lambdas
  * To make independent from the context-ness inference.
  * They have unique name in the enclosing scope, so no conflict will occur.