Win64 linking fix for std.c.windows.com

Linking with LINK.EXE from VisualStudio 2012 Express Desktop results in the following linker errors:
```
phobos64.lib(com_151d_376.obj) : error LNK2019: unresolved external symbol __imp
_InterlockedDecrement referenced in function _D3std1c7windows3com9ComObject7Rele
aseMWZk
phobos64.lib(com_151d_376.obj) : error LNK2019: unresolved external symbol __imp
_InterlockedIncrement referenced in function _D3std1c7windows3com9ComObject6AddR
efMWZk
C:\Users\sludwig\AppData\Local\Temp\.rdmd\source\150067089-krtek.exe : fatal err
or LNK1120: 2 unresolved externals
--- errorlevel 1120
```

Using atomicOp instead of InterlockedIncrement here to avoid those.