fix Issue 13095 - Someteims  destructor is called if constructor throws
fix Issue 4421 - Union propagates copy constructors and destructors over all members
fix Issue 13694 - Typesafe variadic function template overload fails to match to any template
Merge pull request #4101 from WalterBright/fix13095

fix Issue 13095 - Sometimes struct  destructor is called if constructor throws
Merge pull request #4144 from WalterBright/fix4421

fix Issue 4421 - Union propagates copy constructors and destructors over all members
Merge pull request #4145 from 9rnsr/fix13694

[REG2.067a] Issue 13694 - Typesafe variadic function template overload fails to match to any template