Fix some assembler issues: The assembler was miscompiling "add" (specifically, the "add reg/mem, imm" variations). The change that caused this seems to have been made because without it, some "add"s didn't compile at all. This patch reverts the previous change, and makes sure assembler operands are remapped correctly even though the input operands auto-generated due to updating operations aren't explicitly used.

// D runtime support helpers

bool LLVM_D_InitRuntime();
void LLVM_D_FreeRuntime();

llvm::Function* LLVM_D_GetRuntimeFunction(llvm::Module* target, const char* name);

llvm::GlobalVariable* LLVM_D_GetRuntimeGlobal(llvm::Module* target, const char* name);