Fix buffer sizes used for map names (64 -> MAX_PATH).

As more games are now supporting maps nested in subfolders or in folders outside of the maps folder,
we need to account for the full path that the game uses to refer to the map for compatibility. Many other
places for fixed for this already after CS:GO added Steam Workshop support for maps.

plugins/nextmap.sp

@@ -86,8 +86,8 @@ public void OnPluginStart()
 	RegConsoleCmd("listmaps", Command_List);
 
 	// Set to the current map so OnMapStart() will know what to do
-	char currentMap[64];
-	GetCurrentMap(currentMap, 64);
+	char currentMap[PLATFORM_MAX_PATH];
+	GetCurrentMap(currentMap, sizeof(currentMap));
 	SetNextMap(currentMap);
 }
 
@@ -98,9 +98,9 @@ public void OnMapStart()
  
 public void OnConfigsExecuted()
 {
-	char lastMap[64], currentMap[64];
+	char lastMap[PLATFORM_MAX_PATH], currentMap[PLATFORM_MAX_PATH];
 	GetNextMap(lastMap, sizeof(lastMap));
-	GetCurrentMap(currentMap, 64);
+	GetCurrentMap(currentMap, sizeof(currentMap));
 	
 	// Why am I doing this? If we switched to a new map, but it wasn't what we expected (Due to sm_map, sm_votemap, or
 	// some other plugin/command), we don't want to scramble the map cycle. Or for example, admin switches to a custom map
@@ -146,8 +146,8 @@ void FindAndSetNextMap()
 	
 	if (g_MapPos == -1)
 	{
-		char current[64];
-		GetCurrentMap(current, 64);
+		char current[PLATFORM_MAX_PATH];
+		GetCurrentMap(current, sizeof(current));
 
 		for (int i = 0; i < mapCount; i++)
 		{