Symbol specialization in auto_optimizer() never took effect. (#1410)

The `dict` that was storing all the symbols, `known_symbols`, was
emptied just after its creation. The efect was that the specialization
never took effect.

---------

Co-authored-by: Philipp Schaad <schaad.phil@gmail.com>

dace/transformation/auto/auto_optimize.py

@@ -646,7 +646,6 @@ def auto_optimize(sdfg: SDFG,
 
     if symbols:
         # Specialize for all known symbols
-        known_symbols = {s: v for (s, v) in symbols.items() if s in sdfg.free_symbols}
         known_symbols = {}
         for (s, v) in symbols.items():
             if s in sdfg.free_symbols: