Wrong ogre library loaded at runtime when Ogre1.x and Ogre2.x are both installed

**Original report ([archived issue](https://osrf-migration.github.io/ignition-gh-pages/#!/ignitionrobotics/ign-rendering/issues/36)) by Ian Chen (Bitbucket: [Ian Chen](https://bitbucket.org/%7Beaa6fca5-6deb-43f6-907f-971c144735dd%7D/), GitHub: [iche033](https://github.com/iche033)).**

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# Description
Compilation works fine and the correct version of ogre libraries are linked but the wrong version of ogre library gets loaded during run time. It always loads the first libOgreMain.so it finds in the path, resulting in memory corruption when a test or a demo is run.

# Steps to Reproduce
1. Install ogre 1.9 (e.g. libogre-1.9-dev)

1. install ogre 2.1 (e.g. from source into $HOME/local)

1. build ign-rendering

1. run `make test`

**Expected behavior:**

tests run without crashing

**Actual behavior:**

test crashes with a msg about memory corruption