dmd 1.048 and 2.033 releases

[#ponce]

> 
> Somewhere in the huge thread(s) on the topic Walter mentioned the optimizer 
> does (some of) the required flow analysis, so presumably it needs to run in 
> order for this to work.

I think it's disabled in debug mode to keep the compilation time low. 
I guess it's more expensive CPU-wise than escape analysis which is done in both modes.
So it seems the right thing to do for me.