Preprocessor: remove unused steady_state_growth option to pac_model

(manually cherry picked from commit 014e18df)

preprocessor @ 784b2d6d

-Subproject commit 0ccb986da8539ee7cd9e1d115ba2d3a094adb076
+Subproject commit 784b2d6d4081dcbfd45d94a327236f27a1bc8ead

tests/pac/trend-component-1-mce/example_det.mod

@@ -30,7 +30,7 @@ gamma =  .7;
 
 trend_component_model(model_name=toto, eqtags=['eq:x1', 'eq:x2', 'eq:x1bar', 'eq:x2bar'], targets=['eq:x1bar', 'eq:x2bar']);
 
-pac_model(discount=beta, model_name=pacman, steady_state_growth=.0);
+pac_model(discount=beta, model_name=pacman);
 
 model;
 
@@ -65,4 +65,4 @@ shocks;
 end;
 
 perfect_foresight_setup(periods=50);
-perfect_foresight_solver;
\ No newline at end of file
+perfect_foresight_solver;

tests/pac/trend-component-2-mce/example_sto.mod

@@ -30,7 +30,7 @@ gamma =  .7;
 
 trend_component_model(model_name=toto, eqtags=['eq:x1', 'eq:x2', 'eq:x1bar', 'eq:x2bar'], targets=['eq:x1bar', 'eq:x2bar']);
 
-pac_model(discount=beta, model_name=pacman, steady_state_growth=.0);
+pac_model(discount=beta, model_name=pacman);
 
 model(linear);
 
@@ -74,4 +74,4 @@ var ex2bar = .0;
 var ez = .02; 
 end;
 
-stoch_simul(periods=1000, noprint);
\ No newline at end of file
+stoch_simul(periods=1000, noprint);