Fix #28555: Save as Runtime addon not working in 2.59

Temporary mainfile used to be saved to current working directory
which isn't always available for writting.
Save temporary mainfile to temporary directory.

game_engine_save_as_runtime.py

@@ -35,6 +35,7 @@ import bpy
 import os
 import sys
 import shutil
+import tempfile
 
 
 def CopyPythonLibs(dst, overwrite_lib, report=print):
@@ -104,7 +105,8 @@ def WriteRuntime(player_path, output_path, copy_python, overwrite_lib, copy_dlls
     file.close()
     
     # Create a tmp blend file (Blenderplayer doesn't like compressed blends)
-    blend_path = bpy.path.clean_name(output_path)
+    tempdir = tempfile.mkdtemp()
+    blend_path = os.path.join(tempdir, bpy.path.clean_name(output_path))
     bpy.ops.wm.save_as_mainfile(filepath=blend_path,
                                 relative_remap=False,
                                 compress=False,
@@ -119,6 +121,7 @@ def WriteRuntime(player_path, output_path, copy_python, overwrite_lib, copy_dlls
 
     # Get rid of the tmp blend, we're done with it
     os.remove(blend_path)
+    os.rmdir(tempdir)
     
     # Create a new file for the bundled runtime
     output = open(output_path, 'wb')