Decrease DMD memory usage

[Temtaime]

Yes, it uses msvc runtimes, but ICC can optimize much more than 
VC.

I've tried to combine DMD with tcmalloc which handles memory 
allocations better than built-in malloc.

My project building duration is 9 sec.
This is more than twice faster than DM's DMD without any compiler 
logic change!

http://acomirei.ru/u/dmd_1.exe

Okay, i'll try compile DMD with VC 2012 also.