Fix suitableForSymExec precedence inversion

`not $ null m.inputs && ...` parsed as `not (null m.inputs && ...)`,
negating the whole conjunction: the dynamic-argument guard never fired
(so bytes/string/dynamic-array methods were handed to the symbolic
encoder, which throws).
Bind `not` to the emptiness check alone so the filter means what it
says: explore methods that have arguments, none dynamic, not opted out.

Author: elopez

lib/Echidna/SymExec/Common.hs

@@ -83,7 +83,12 @@ extractErrors = mapMaybe (\case
   _ -> Nothing)
 
 suitableForSymExec :: Method -> Bool
-suitableForSymExec m = not $ null m.inputs
+suitableForSymExec m =
+  -- the method must take arguments (otherwise there is nothing to solve for),
+  -- none of which may be a dynamic ABI type (hevm's symAbiArg cannot encode
+  -- bytes/string/dynamic arrays symbolically and throws), and it must not opt
+  -- out via a `_no_symexec` name.
+  not (null m.inputs)
   && null (filter (\(_, t) -> abiKind t == Dynamic) m.inputs)
   && not (T.isInfixOf "_no_symexec" m.name)