remove build warnings

src/alpm_config.vala

@@ -42,7 +42,7 @@ class AlpmRepo {
 
 }
 
-class AlpmConfig {
+public class AlpmConfig {
 	string conf_path;
 	string? rootdir;
 	string? dbpath;

src/mirrors_config.vala

@@ -18,7 +18,7 @@
  */
 
 namespace Pamac {
-	class MirrorsConfig {
+	public class MirrorsConfig {
 		string conf_path;
 
 		public string choosen_generation_method { get; private set; }

src/pamac_config.vala

@@ -18,7 +18,7 @@
  */
 
 namespace Pamac {
-	class Config {
+	public class Config {
 		string conf_path;
 		HashTable<string,string> _environment_variables;