Rewrite `StructLiteralExp::toElem` to store individual fields instead of generating a constant to fill the entire struct with a single `store`. This is much more efficient at compile time (fixing #320) and vastly reduces the size of the emitted code. Since LLVM no longer needs to keep the data for all fields in "registers" until the store happens, it should also be more efficient at run time in cases where the fields aren't assigned with constants. There's also some code clean-up by removing duplicated logic.

#ifndef __LDC_GEN_ABI_X86_64_H__
#define __LDC_GEN_ABI_X86_64_H__

#include "gen/abi.h"


TargetABI* getX86_64TargetABI();


#endif