Fixed compiler warning.

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@7578 178a84e3-b1eb-0310-8ba1-8eac791a3b58

src/graphics/particle_kind_manager.cpp

@@ -86,6 +86,7 @@ ParticleKind* ParticleKindManager::getParticles(const char* name)
         }
         catch (std::runtime_error& e)
         {
+            (void)e;   // remove compiler warning
             // not found in track directory, let's try globally...
         }
     }