Implemented get_num_cpus() for Linux.
Implemented get_num_cpus() for Linux.

git-svn-id: 9f18dd852162ff6c59c5533c0914e9cf81af9e7c@244 d8a29897-7e4b-0410-a74a-8bb4c295346f

elventear/psutil,elventear/psutil