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 -qlpv candlepin-tomcat6-0.9.2-1.git.30.d46a1ac.el6_5.noarch.rpm  | grep c3p0
lrw-r--r--    1 tomcat  tomcat                     24 Feb  6 12:49 /var/lib/tomcat6/webapps/candlepin/WEB-INF/lib/c3p0.jar -> /usr/share/java/c3p0.jar
lrw-r--r--    1 tomcat  tomcat                     35 Feb  6 12:49 /var/lib/tomcat6/webapps/candlepin/WEB-INF/lib/hibernate4-c3p0.jar -> /usr/share/java/hibernate4-c3p0.jar
$ 
```
The original build did not have the jar:
```
$ rpm -qlpv candlepin-tomcat6-0.9.2-1.el6_5.noarch.rpm | grep c3p0
lrw-r--r--    1 tomcat  tomcat                     24 Jan 15 15:45 /var/lib/tomcat6/webapps/candlepin/WEB-INF/lib/c3p0.jar -> /usr/share/java/c3p0.jar
$
```