File with the description of the "encoding declaration".  It doesn't work.

Because of "pyflakes.api.check" function does not assume that passed the Unicode string.

example
```python
# coding: utf-8

import math
import re
import os
import random
import multiprocessing
import grp, pwd, platform
import subprocess, sys

def foo():
    from abc import ABCMeta, WeakSet
    try:
        import multiprocessing
        print(multiprocessing.cpu_count())
    except ImportError as exception:
        print(sys.version)
    return math.pi
```

expected
```python
# coding: utf-8
import math
import sys


def foo():
    try:
        import multiprocessing
        print(multiprocessing.cpu_count())
    except ImportError as exception:
        print(sys.version)
    return math.pi
```

However, because not to be so now, I sent a pull request to fix it.

Thank you for reading it through.