The problem is the base AMI's from AWS don't have the correct base compile to work with ClouSE. You need to pull down the original MySQL libraries and compile them locally. Then the .so files recognize the fastmutex symbol.
I'm not using ubuntu, but similar to:
Got MySQL 5.5.20 tar from mysql.com:
Followed the instructions in the INSTALL-BINARY file:
tar xzf mysql-5.5.20-linux2.6-x86_64.tar.gz
sudo mv mysql-5.5.20-linux2.6-x86_64 /usr/local/
sudo chown -R mysql:mysql mysql-5.5.20-linux2.6-x86_64
sudo ln -s mysql-5.5.20-linux2.6-x86_64 mysql
sudo mysql/scripts/mysql_install_db --user=mysql
If you do this procedure, make sure you're then running the correct MySQL and are using the correct plugin directory. It will most likely change.
Let me know if this helps, the rest of the config should be more or less same as before.