fix "rake unittests failed!" issue on centos/scientific linux 6.4

- disable shared library of cmockery
- remove '-static' option of ld
```
    (test in centos and scientific linux 6.4 w/ ruby1.9.3)
    $ sudo -s
    # yum install http://rdo.fedorapeople.org/openstack/openstack-grizzly/rdo-release-grizzly.rpm
    # yum update
    # yum install gcc make git ruby193-ruby ruby193-ruby-devel libpcap-devel sqlite-devel glib2-devel
    # echo /opt/rh/ruby193/root/usr/lib64 > /etc/ld.so.conf.d/ruby193-x86_64.conf
    # ldconfig
    # /opt/rh/ruby193/root/usr/bin/gem install bundler
    # exit
    $ export PATH=$PATH:/opt/rh/ruby193/root/usr/bin:/opt/rh/ruby193/root/usr/local/bin
    $ mkdir work
    $ cd work
    $ git clone https://github.com/trema/trema.git
    $ cd trema
    $ bundle config --local path vendor/bundle
    $ ./cruise.rb --all
    ...
    /usr/bin/ld: cannot find -lsqlite3
    ...
    'bundle exec rake unittests' failed!
    ...
    (centos/scientific linux does not provide a static library of sqlite3)
```