[LDC] Fix SPIRV build on Windows

Author: kinke

llvm/lib/Target/SPIRV/SPIRVBuiltins.cpp

@@ -1733,7 +1733,8 @@ static bool generateConvertInst(const StringRef DemangledCall,
                     SPIRV::Decoration::SaturatedConversion, {});
   if (Builtin->IsRounded)
     buildOpDecorate(Call->ReturnRegister, MIRBuilder,
-                    SPIRV::Decoration::FPRoundingMode, {Builtin->RoundingMode});
+                    SPIRV::Decoration::FPRoundingMode,
+                    {static_cast<uint32_t>(Builtin->RoundingMode)});
 
   unsigned Opcode = SPIRV::OpNop;
   if (GR->isScalarOrVectorOfType(Call->Arguments[0], SPIRV::OpTypeInt)) {