The RPM repository of PostgreSQL has hosted a version of pg_top. pg_top was first included in the 9.0 repository and continued to be included in the 9.2 and 9.3 repositories. The 9.4 repository lacks it.
Compare the 9.4 repository with the 9.3 repository regarding the "pg_top93-3.7.0-1.rhel6.x86_64.rpm" package.