[Bf-taskforce25] Compile error on osx

[Mats Holmberg]

Trying to compile on osx with scons gives this:

Updated to revision 22295.
Traceback (most recent call last):
 File "scons/scons.py", line 66, in <module>
   if os.environ.has_key("SCONS_LIB_DIR"):
AttributeError: '_Environ' object has no attribute 'has_key'

Cheers,
-mats