Fix minor windows pedantic warnings.

src/GameState.cpp

@@ -2369,15 +2369,18 @@ bool GameState::ChangePreferredDifficulty( PlayerNumber pn, int dir )
 	const vector<Difficulty> &v = CommonMetrics::DIFFICULTIES_TO_SHOW.GetValue();
 
 	Difficulty d = GetClosestShownDifficulty(pn);
-	while( 1 )
+	for(;;)
 	{
 		d = enum_add2( d, dir );
 		if( d < 0 || d >= NUM_Difficulty )
+		{
 			return false;
+		}
 		if( find(v.begin(), v.end(), d) != v.end() )
+		{
 			break; // found
+		}
 	}
-
 	m_PreferredDifficulty[pn].Set( d );
 	return true;
 }
@@ -2424,17 +2427,22 @@ bool GameState::ChangePreferredCourseDifficulty( PlayerNumber pn, int dir )
 	const vector<CourseDifficulty> &v = CommonMetrics::COURSE_DIFFICULTIES_TO_SHOW.GetValue();
 
 	CourseDifficulty cd = m_PreferredCourseDifficulty[pn];
-	while( 1 )
+	for(;;)
 	{
 		cd = enum_add2( cd, dir );
 		if( cd < 0 || cd >= NUM_Difficulty )
+		{
 			return false;
+		}
 		if( find(v.begin(),v.end(),cd) == v.end() )
+		{
 			continue; /* not available */
+		}
 		if( !pCourse || pCourse->GetTrail( GetCurrentStyle(pn)->m_StepsType, cd ) )
+		{
 			break;
+		}
 	}
-
 	return ChangePreferredCourseDifficulty( pn, cd );
 }