esp-idf: Missing std::to_string C++ support (libstdc++) (IDFGH-133)

I notice that std::to_string support is missing from the libstdc++, not sure what it takes to get that added, but it is useful especially when porting other C++11 code.

Specifically, the following app_main should work. The example usage is directly from cppreference: http://www.cplusplus.com/reference/string/to_string/ (it currently fails to compile)

// to_string example
#include <iostream>   // std::cout
#include <string>     // std::string, std::to_string

#ifdef __cplusplus
extern "C"
#endif // __cplusplus
void app_main()
{
  std::string pi = "pi is " + std::to_string(3.1415926);
  std::string perfect = std::to_string(1+2+4+7+14) + " is a perfect number";
  std::cout << pi << '\n';
  std::cout << perfect << '\n';
}

The error I see when running make:

./hello_world_main.cpp: In function 'void app_main()':
./hello_world_main.cpp:10:31: error: 'to_string' is not a member of 'std'
   std::string pi = "pi is " + std::to_string(3.1415926);
                               ^
./hello_world_main.cpp:11:25: error: 'to_string' is not a member of 'std'
   std::string perfect = std::to_string(1+2+4+7+14) + " is a perfect number";
                         ^
make[1]: *** [hello_world_main.o] Error 1
make: *** [component-main-build] Error 2