fix Issue 11203

- fixup #614 - disable finalization for extern(C++) classes

- BlkAttr is already default initialized to BlkAttr.FINALIZE
  so we have to clear the bit for C++ classes.
Merge pull request #633 from dawgfoto/fix11203

fix Issue 11203
remove redundant BlkAttr declarations

- use core.memory.GC.BlkAttr
- add private BlkAttr alias to replace declarations
- replace BlkAttr.ALL_BITS with ~BlkAttr.NONE
Merge pull request #634 from dawgfoto/blkAttr

remove redundant BlkAttr declarations
use int instead of bool for C function rt_unloadLibrary

- This should actually be ABI compatible but it's cleaner
  for documentation purpose.
Merge pull request #623 from dawgfoto/rt_loadLibrary

use int instead of bool for C function rt_unloadLibrary
Add declaration of CP_UTF8
Merge pull request #637 from JakobOvrum/cputf8

Add declaration of CP_UTF8
made windows stack traces 10 times faster
Merge pull request #638 from Ingrater/fastTrace

made windows stack traces 10 times faster
remove unnecessary try/catch block in nothrow method
refactor Duration._toStringImpl to reduce code and object size
Merge pull request #640 from dawgfoto/refactorDurationToStringImpl

refactor Duration._toStringImpl to reduce code and object size
Merge with upstream