flow: print the startup-banner only on the first rank

thanks to [at]atgeirr for catching this.

flow/flow.cpp

@@ -138,7 +138,8 @@ int main(int argc, char** argv)
         return 1;
     }
 
-    Opm::FlowMainEbos<PreTypeTag>::printBanner();
+    if (outputCout)
+        Opm::FlowMainEbos<PreTypeTag>::printBanner();
 
     // Create Deck and EclipseState.
     try {

opm/autodiff/FlowMainEbos.hpp

@@ -19,7 +19,6 @@
   You should have received a copy of the GNU General Public License
   along with OPM.  If not, see <http://www.gnu.org/licenses/>.
 */
-
 #ifndef OPM_FLOW_MAIN_EBOS_HEADER_INCLUDED
 #define OPM_FLOW_MAIN_EBOS_HEADER_INCLUDED