Fix a conflict with the `newrelic_rpm` gem.

Issue: https://github.com/peek/peek-gc/issues/2

When someone else (NewRelic or whoever) has already enabled `GC::Profiler`, don't `clear` out the profile before they get a chance to do so.
Merge pull request #1 from TALlama/master

Fix a conflict with the `newrelic_rpm` gem.