Avoid infinite loops in loplugin

...introduced with cab6e68369 "Make
checkIdenticalDefaultArguments more precise", causing older Clang to hang when
compiling specific LO source files.

Change-Id: I99cfcad2f0cd9adccd5aa84d21502f586762217f

compilerplugins/clang/plugin.cxx

@@ -292,6 +292,7 @@ Plugin::IdenticalDefaultArgumentsResult Plugin::checkIdenticalDefaultArguments(
         if (ce1->getNumArgs() == 0 && ce2->getNumArgs() == 0) {
             return IdenticalDefaultArgumentsResult::Yes;
         }
+        break;
     }
     return IdenticalDefaultArgumentsResult::Maybe;
 }