Issue #20597: Remove unused definition of PATH_MAX on Windows, MAXPATHLEN is
now preferred. Patch written by Jeffrey Armstrong.
Issue #20597, #21274: Remove unused definition of PATH_MAX on GNU/Hurd,
MAXPATHLEN is now preferred.
asyncio: Move loop attribute to _FlowControlMixin

Move the _loop attribute from the constructor of _SelectorTransport,
_ProactorBasePipeTransport and _UnixWritePipeTransport classes to the
constructor of the _FlowControlMixin class.

Add also an assertion to explicit that the parent class must ensure that the
loop is defined (not None)
(Merge 3.4) asyncio: Move loop attribute to _FlowControlMixin

Move the _loop attribute from the constructor of _SelectorTransport,
_ProactorBasePipeTransport and _UnixWritePipeTransport classes to the
constructor of the _FlowControlMixin class.

Add also an assertion to explicit that the parent class must ensure that the
loop is defined (not None)