erasure-code: do not leak shec instance on failure

If the shec plugin fails to initialize the instance, it must be deleted
before returning to the caller, otherwise it will be leaked.

Signed-off-by: Loic Dachary <ldachary@redhat.com>

src/erasure-code/shec/ErasureCodePluginShec.cc

@@ -59,6 +59,7 @@ public:
     }
     int r = interface->init(profile);
     if (r) {
+      delete interface;
       return r;
     }
     *erasure_code = ErasureCodeInterfaceRef(interface);