DoubleToStringConverter::EcmaScriptConverter() not thread safe on Windows

From http://code.google.com/p/double-conversion/issues/detail?id=30 :

-- sean.parent
Code inspection at: double-conversion.cc:44

Function level statics are not initialized in a thread safe manner with Visual Studio 2012 or prior. With gcc and clang thread safe initialization is optional (though required by C++11).

Could be fixed with any number of once init mechanisms, or aggregate initialization.

-- floitsch
I don't see any easy way of solving this without pulling in thread-specific headers.
I would rather just require -std=c++0x which, afaik, guarantees correct initialization.
I will discuss this with my colleagues next week and see if somebody comes up with a better solution.

-- stephen.mercer
If you simply move the function static out of the function and make it static to the file then it will be thread safe initialized. Reference this answer:
http://stackoverflow.com/questions/1962880/is-c-static-member-variable-initialization-thread-safe

So to make it thread safe, simply replace this code (and similar if you have other function-level statics):

```
const DoubleToStringConverter& DoubleToStringConverter::EcmaScriptConverter() {
int flags = UNIQUE_ZERO | EMIT_POSITIVE_EXPONENT_SIGN;
static DoubleToStringConverter converter(flags,
"Infinity",
"NaN",
'e',
-6, 21,
6, 0);
return converter;
}
```

with this code:

```
static DoubleToStringConverter kConverter(UNIQUE_ZERO | EMIT_POSITIVE_EXPONENT_SIGN,
"Infinity",
"NaN",
'e',
-6, 21,
6, 0);

const DoubleToStringConverter& DoubleToStringConverter::EcmaScriptConverter() {
return kConverter;
}
```

-- rafaelefernandez
You definitely do not want to move it out of the function because then you will run into the static initialization order problem.