symlink hibernate4-c3p0 jar

We forgot to symlink hibernate4-c3p0.

This is the scratch build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=7013103

Here are the results for the scratch build:
```
$ rpm -qlp candlepin-tomcat6-0.9.2-1.git.30.d46a1ac.el6_5.noarch.rpm  | grep c3p0
/var/lib/tomcat6/webapps/candlepin/WEB-INF/lib/c3p0.jar
/var/lib/tomcat6/webapps/candlepin/WEB-INF/lib/hibernate4-c3p0.jar
$ 
```
The original build did not have the jar:
```
$ rpm -qlp candlepin-tomcat6-0.9.2-1.el6_5.noarch.rpm | grep c3p0
/var/lib/tomcat6/webapps/candlepin/WEB-INF/lib/c3p0.jar
$
```