<iostream> not usable

The inclusion of some standard library headers can cause compilation errors. For example:
```C++
#include
void setup() {
}
void loop() {
}
```
```
C:\Users\vhtmf\AppData\Local\Temp\arduino\sketches\4F283322D1DC7D231547A617FD5B3E64\sketch\sketch_feb10a.ino.cpp.o: In function `__static_initialization_and_destruction_0':
c:\users\vhtmf\appdata\local\arduino15\packages\arduino\tools\arm-none-eabi-gcc\4.8.3-2014q1\arm-none-eabi\include\c++\4.8.3/iostream:74: undefined reference to `std::ios_base::Init::Init()'
c:\users\vhtmf\appdata\local\arduino15\packages\arduino\tools\arm-none-eabi-gcc\4.8.3-2014q1\arm-none-eabi\include\c++\4.8.3/iostream:74: undefined reference to `std::ios_base::Init::~Init()'
collect2.exe: error: ld returned 1 exit status

exit status 1

Compilation error: exit status 1
```
It seems that there are some functions declared in the header file that are not defined.

The standard library does not appear to be in this repository. Does anyone know where it's downloaded from? I installed the standard library automatically after installing the Arduino SAM Boards in the Arduino IDE Board Manager.

Start by reproducing the minimal sketch containing #include with the Arduino SAM Boards toolchain and inspect the reported linker failure. Read the Arduino SAM build configuration and the arm-none-eabi C++ standard-library setup; done means the sketch compiles and links without the undefined std::ios_base::Init symbols.

Written by the indexing model from the issue text.