Fix formatting type annotations for tuples with more than two arguments

[mitya57]

Currently in Python 3.6, Sphinx formats this function:

def foo() -> Tuple[int, str, int]:
    pass

in the following way (which can be seen in the Travis log for the first commit in this PR):

() -> Tuple[[int, str], int]

This is because the tuple gets treated as a function, and the last int is treated like a return value.
This affects only format_annotation_old function. format_annotation_new which is used for Python 3.7 is not affected.

This pull request fixes this bug, and adds a test.

There is a hasattr(annotation, '__tuple_params__') clause below in that function. I am not sure for which Python version it is because all versions I tested (2.7, 3.5, 3.6, 3.7) do not have this attribute. Maybe it is for 3.4? Anyway I added an opposite condition (not hasattr) to be on the safe side.

[codecov]

Codecov Report

Merging #5167 into 1.7 will increase coverage by <.01%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##              1.7    #5167      +/-   ##
==========================================
+ Coverage   82.04%   82.04%   +<.01%     
==========================================
  Files         283      288       +5     
  Lines       37834    38161     +327     
  Branches     5860     5916      +56     
==========================================
+ Hits        31040    31309     +269     
- Misses       5486     5534      +48     
- Partials     1308     1318      +10

Impacted Files	Coverage Δ
tests/test_util_inspect.py	90.12% <100%> (+0.08%)	⬆️
sphinx/util/inspect.py	73.42% <100%> (+0.25%)	⬆️
tests/typing_test_data.py	62.85% <50%> (-0.78%)	⬇️
sphinx/builders/html.py	82.76% <0%> (-0.12%)	⬇️
sphinx/search/__init__.py	95.11% <0%> (ø)
sphinx/apidoc.py	0% <0%> (ø)
sphinx/__init__.py	57.5% <0%> (ø)
sphinx/quickstart.py	0% <0%> (ø)
sphinx/errors.py	68.42% <0%> (ø)

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[tk0miya]

LGTM!