[D-runtime] DLL initialization in Druntime

[Rainer Schuetze]

Walter Bright wrote:
>> BTW: there is a regression in 2.051 regarding DLLs in a multi-threading
>> environment: http://d.puremagic.com/issues/show_bug.cgi?id=5382
> 
> This is a mystery, as there is no such variable in src/core/dll_helper.d
> 

Maybe the diff shows the wrong direction patched <-> original.
Using _moduleinfo_tlsdtors_i from object_.d no longer works, so the 
patch adds tlsCtorRun.