COMP: Invalid conversion detected by clang c++11

Removed private member function that is never used
by the class.

istream::operator>> returns a reference to an istream
that is not convertable to a boolean.

istream& operator>> (long& val);

This test case confirms that this is really invalid code:

cat test_conversion.cpp
\#include <iostream>
\#include <sstream>
\#include <string>
int main(int argc, char * argv[])
{
  typedef long int DataObjectPointerArraySizeType;
  DataObjectPointerArraySizeType idx;
  std::string idxStr = "7";
  return (std::istringstream(idxStr) >> idx);
}

clang++ -std=c++11 test_conversion.cpp

test_conversion.cpp:9:10: error: no viable conversion from 'std::__1::basic_istream<char>' to 'int'
  return (std::istringstream(idxStr) >> idx);
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Change-Id: I1979f063af664c7782ddfc73d539973631e13d9c
COMP: Non standard conversion for -std=c++11

A compiler error was encounted for invalid conversion
when compiling in strict c++11 mode.

ITKv4/Modules/Numerics/Optimizers/src/itkCumulativeGaussianOptimizer.cxx:413:48: error:
      invalid operands to binary expression ('basic_ostream<char, std::__1::char_traits<char> >' and 'const std::ostringstream'
      (aka 'const basic_ostringstream<char>'))
  os << indent << "StopConditionDescription: " << m_StopConditionDescription << std::endl;
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/ostream:190:20: note:
    candidate function not viable: no known conversion from 'const std::ostringstream' (aka 'const basic_ostringstream<char>')
    to 'const void *' for 1st argument; take the address of the argument with &
    basic_ostream& operator<<(const void* __p);
                   ^

Change-Id: I02535cf4c3dae9152bf03a33e884a62224fa0731
Merge topic 'UnusedFunction'

c52c567 COMP: Non standard conversion for -std=c++11
6a6faab COMP: Invalid conversion detected by clang c++11