Fixed a nasty bug with how interface vtables for class initializers were output, causing some class fields to be skipped. Fixed a problem in definition of ClassInfos where an invalid constant was potentially used. This needs to be looked into proper as it might happen again in the future.

// 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);