Fix header and pre-declarations in QLA cooling

src/cooling/QLA/cooling.h

@@ -33,6 +33,9 @@ struct cosmology;
 struct hydro_props;
 struct entropy_floor_properties;
 struct space;
+struct unit_system;
+struct phys_const;
+struct swift_params;
 
 void cooling_update(const struct cosmology *cosmo,
                     struct cooling_function_data *cooling, struct space *s);

src/cooling/QLA/cooling_io.h

@@ -24,6 +24,7 @@
 
 /* Local includes */
 #include "cooling.h"
+#include "engine.h"
 #include "io_properties.h"
 
 #ifdef HAVE_HDF5