Add a default constructor to AsmWriterOperand to make VS2008sp1 happy. (AsmWriterOperand is used in a std::pair, and VS need to generate the default constructor of this pair).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58185 91177308-0d34-0410-b5e6-96231b3b80d8

utils/TableGen/AsmWriterEmitter.cpp

@@ -45,6 +45,9 @@ namespace llvm {
     /// an operand, specified with syntax like ${opname:modifier}.
     std::string MiModifier;
 
+	// To make VS STL happy
+	AsmWriterOperand():OperandType(isLiteralTextOperand) {}
+
     AsmWriterOperand(const std::string &LitStr)
       : OperandType(isLiteralTextOperand), Str(LitStr) {}