Remove initialization of padding of reals, ireals and creals. According to the spec and C ABIs, the contents of padding is undefined. This was breaking dstress creal_01,02,03,07,08,09 and 20 on x86-64. The code was apparently added to fix creal_13,14 and 15, which explicitly compare padding and assert if it's different. I'd argue those tests are broken. (Also, on x86-64 they *also* fail) The tests this fixes, on the other hand, are basic arithmetic.

// 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);