Build failure when scons uses python 3

[ryandesign]

As reported to MacPorts, field3d does not build when scons uses python 3:

scons: Reading SConscript files ...
  File "BuildSupport.py", line 276

    print cmd

    ^^^^^^^^^

SyntaxError: Missing parentheses in call to 'print'. Did you mean print(...)?

[ryandesign]

The next error after that is:

AttributeError: 'dict' object has no attribute 'has_key':
  File "SConstruct", line 46:
    SConscript("SConscript")
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/SCons/Script/SConscript.py", line 660:
    return method(*args, **kw)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/SCons/Script/SConscript.py", line 597:
    return _SConscript(self.fs, *files, **subst_kw)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/SCons/Script/SConscript.py", line 285:
    exec(compile(scriptdata, scriptname, 'exec'), call_stack[-1].globals)
  File "SConscript", line 49:
    setupEnv(libEnv)
  File "BuildSupport.py", line 231:
    env.SetOption('num_jobs', numCPUs())
  File "BuildSupport.py", line 253:
    if os.sysconf_names.has_key("SC_NPROCESSORS_ONLN"):

From python 3 documentation:

Removed. dict.has_key() – use the in operator instead.