Add template specialization back

Author: velconia

paddle/fluid/string/printf.h

@@ -83,6 +83,13 @@ void Fprintf(std::ostream& out, const char* fmt, const Args&... args) {
   tinyformat::vformat(out, fmt, tinyformat::makeFormatList(args...));
 }
 
+template <typename... Args>
+std::string Sprintf(const Args&... args) {
+  std::ostringstream oss;
+  Fprintf(oss, "");
+  return oss.str();
+}
+
 template <typename... Args>
 std::string Sprintf(const char* fmt, const Args&... args) {
   std::ostringstream oss;