The $CXX environment variable is not exported under the 'c' language on Travis.

Based on patch by Vajrasky Kok.

Added the documentation for PyUnicode_Translate().

This will eliminate one of the builds in Travis, allowing for CI overall to complete faster.

The module is implicitly tested through test_urllib.

Initial patch by Vajrasky Kok.

Many metaclasses in the standard library don't play nice with
__init_subclass__. This bug makes ABCMeta in particular with
__init_subclass__, which is an 80/20 solution for me personally.
AFAICT, a general solution to this problem requires updating all
metaclasses in the standard library to make sure they pass **kwargs to
type.__new__, whereas this PR only fixes ABCMeta. For context, see
https://bugs.python.org/issue29581.

* added a test combining ABCMeta and __init_subclass__
* Added NEWS item

See https://github.com/python/cpython/pull/201#discussion_r103229425.

* Add _PyObject_HasFastCall()
* partial_call() now avoids temporary tuple to pass positional
  arguments if the callable supports the FASTCALL calling convention
  for positional arguments.
* Fix also a performance regression in partial_call() if the callable
  doesn't support FASTCALL.

Call abs_paths() only if removeduppaths() changed sys.path

PyEval_Call* APIs are not documented and they doesn't respect PY_SSIZE_T_CLEAN.
So add comment block which recommends PyObject_Call* APIs to ceval.h.

This commit also changes PyEval_CallMethod and PyEval_CallFunction
implementation same to PyObject_CallMethod and PyObject_CallFunction
to reduce future maintenance cost.  Optimization to avoid temporary
tuple are copied too.

PyEval_CallFunction(callable, "i", (int)i) now calls callable(i) instead of
raising TypeError.  But accepting this edge case is backward compatible.

FreeBSD is the only platforms with unsigned FD_SETSIZE.

if attributes "encoding" or "errors" of sys.stdin or sys.stdout
are not set or are not strings.