message: NFC: Change a usage of StringLiteral to StringRef.
  This matches the result type of other functions returning c-string, and fixes a build failure where some compilers fail to construct the StringLiteral.
diff: @@ -51,9 +51,7 @@ public:
  MLIRContext *getContext() const { return context; }
  /// Return the name of the attribute used for symbol names.
  - static constexpr llvm::StringLiteral getSymbolAttrName() {
  - return "sym_name";
  - }
  + static StringRef getSymbolAttrName() { return "sym_name"; }
  private:
  MLIRContext *context;
  