What gcc to use for gdc master?

[Dan Olson via D.gnu]

Dan Olson <gorox at comcast.net> writes:

> Looks like I need to track down missing symbols from rt.tlsgc now. I
> think it is becoming a fun puzzle :-) The arm stuff can wait.

How do I tell gdc that OS X needs target specific underscore "_" prefix
added to pragma(mangle, name)?  thread.d uses
core.internal.traits.externDFunc.  That is cause.  For now I worked
around with:

pragma(mangle, "_"~mangleFunc!T(fqn)) mixin(decl);