setup: inline now-constant list

This varied when we supported Python 2.

Differential Revision: https://phab.mercurial-scm.org/D12276

setup.py

@@ -773,14 +773,10 b' class buildhgexe(build_ext):'
             f.write(b'/* this file is autogenerated by setup.py */\n')
             f.write(b'#define HGPYTHONLIB "%s"\n' % pythonlib)
 
-        macros = None
-        if sys.version_info[0] >= 3:
-            macros = [('_UNICODE', None), ('UNICODE', None)]
-
         objects = self.compiler.compile(
             ['mercurial/exewrapper.c'],
             output_dir=self.build_temp,
-            macros=macros,
+            macros=[('_UNICODE', None), ('UNICODE', None)],
         )
         self.compiler.link_executable(
             objects, self.hgtarget, libraries=[], output_dir=self.build_temp