remove duplicate string_printf

#3594, #3592

src/libslic3r/Utils.hpp

@@ -93,8 +93,6 @@ namespace PerlUtils {
     extern std::string path_to_parent_path(const char *src);
 };
 
-std::string string_printf(const char *format, ...);
-
 // Standard "generated by Slic3r version xxx timestamp xxx" header string, 
 // to be placed at the top of Slic3r generated files.
 std::string header_slic3r_generated();

src/libslic3r/utils.cpp

@@ -577,24 +577,6 @@ namespace PerlUtils {
     std::string path_to_parent_path(const char *src)    { return boost::filesystem::path(src).parent_path().string(); }
 };
 
-
-std::string string_printf(const char *format, ...)
-{
-    va_list args1;
-    va_start(args1, format);
-    va_list args2;
-    va_copy(args2, args1);
-
-    size_t needed_size = ::vsnprintf(nullptr, 0, format, args1) + 1;
-    va_end(args1);
-
-    std::string res(needed_size, '\0');
-    ::vsnprintf(&res.front(), res.size(), format, args2);
-    va_end(args2);
-
-    return res;
-}
-
 std::string header_slic3r_generated()
 {
     return std::string("generated by " SLIC3R_APP_NAME " " SLIC3R_VERSION " on " ) + Utils::utc_timestamp();