Do not redundantly set the message handler

The same message handler is already set up in the constructor.

Author: tautschnig

src/goto-cc/armcc_mode.cpp

@@ -52,7 +52,6 @@ int armcc_modet::doit()
   if(cmdline.isset("verbosity"))
     verbosity=unsafe_string2int(cmdline.get_value("verbosity"));
 
-  compiler.set_message_handler(get_message_handler());
   message_handler.set_verbosity(verbosity);
 
   debug() << "ARM mode" << eom;

src/goto-cc/cw_mode.cpp

@@ -52,7 +52,6 @@ int cw_modet::doit()
   if(cmdline.isset("verbosity"))
     verbosity=unsafe_string2unsigned(cmdline.get_value("verbosity"));
 
-  compiler.set_message_handler(get_message_handler());
   message_handler.set_verbosity(verbosity);
 
   debug() << "CodeWarrior mode" << eom;

src/goto-cc/ms_cl_mode.cpp

@@ -63,7 +63,6 @@ int ms_cl_modet::doit()
   if(cmdline.isset("verbosity"))
     verbosity=unsafe_string2unsigned(cmdline.get_value("verbosity"));
 
-  compiler.set_message_handler(get_message_handler());
   message_handler.set_verbosity(verbosity);
 
   debug() << "Visual Studio mode" << eom;