windows: don’t set `softspace` attribute in `winstdout`

Python 2 file objects have the `softspace` attribute
(https://docs.python.org/2/library/stdtypes.html#file.softspace), which is used
by the print statement to track its internal state. The documentation demands
from file-like objects only that the attribute is writable and initialized to
0. Method `file.write()` sets it to 0, but this is not documented.
Historically, sys.stdout was replaced by an instance of the `winstdout` class,
so it needed to behave exactly the same (the softspace fix was introduced in
705278e70457). Nowadays we don’t replace sys.stdout and don’t use the print
statement on `winstdout` instances, so we can safely drop it.

mercurial/windows.py

@@ -217,8 +217,6 b' class winstdout(object):'
             pass
 
     def write(self, s):
-        if not pycompat.ispy3:
-            self.softspace = 0
         try:
             if not self.throttle:
                 return self.fp.write(s)