Fix user configuration path bug on Linux.

Recent versions of wxWidgets wxStandardPaths::GetUserConfigDir() correctly
append ".config" on Linux build which was incorrect as the current code
already appended it to the path.  Add a check to see if ".config" is the
last path and append as required.

Check for XDG_CONFIG_HOME environment variable on all platforms not just
Linux.

Fixes lp:1769145

https://bugs.launchpad.net/kicad/+bug/1769145

common/common.cpp

@@ -2,8 +2,8 @@
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
  * Copyright (C) 2014-2015 Jean-Pierre Charras, jp.charras at wanadoo.fr
- * Copyright (C) 2008-2015 Wayne Stambaugh <stambaughw@verizon.net>
- * Copyright (C) 1992-2017 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2008 Wayne Stambaugh <stambaughw@gmail.com>
+ * Copyright (C) 1992-2018 KiCad Developers, see AUTHORS.txt for contributors.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -58,14 +58,6 @@ EDA_UNITS_T    g_UserUnit;
 COLOR4D        g_GhostColor;
 
 
-/* Class LOCALE_IO
- * is a class that can be instantiated within a scope in which you are expecting
- * exceptions to be thrown.  Its constructor sets a "C" locale, to read/print files
- * with fp numbers.
- * Its destructor insures that the default locale is restored if an exception
- * is thrown, or not.
- */
-
 std::atomic<unsigned int> LOCALE_IO::m_c_count(0);
 
 LOCALE_IO::LOCALE_IO()
@@ -80,6 +72,7 @@ LOCALE_IO::LOCALE_IO()
     }
 }
 
+
 LOCALE_IO::~LOCALE_IO()
 {
     // use thread safe, atomic operation
@@ -222,20 +215,24 @@ wxString GetKicadConfigPath()
     // http://docs.wxwidgets.org/3.0/classwx_standard_paths.html#a7c7cf595d94d29147360d031647476b0
     cfgpath.AssignDir( wxStandardPaths::Get().GetUserConfigDir() );
 
+    // GetUserConfigDir() does not default to ~/.config which is the current standard
+    // configuration file location on Linux.  This has been fixed in later versions of wxWidgets.
+#if !defined( __WXMSW__ ) && !defined( __WXMAC__ )
+    wxArrayString dirs = cfgpath.GetDirs();
+
+    if( dirs.Last() != ".config" )
+        cfgpath.AppendDir( ".config" );
+#endif
+
     wxString envstr;
 
-    // wxStandardPaths does not default to ~/.config which is the current standard config
-    // location on Linux.  This has been fixed in wxWidgets 3.1.1.
-#if !wxCHECK_VERSION( 3, 1, 1 ) && !defined( __WINDOWS__ ) && !defined( __WXMAC__ )
+    // This shouldn't cause any issues on Windows or MacOS.
     if( wxGetEnv( wxT( "XDG_CONFIG_HOME" ), &envstr ) && !envstr.IsEmpty() )
     {
         // Override the assignment above with XDG_CONFIG_HOME
         cfgpath.AssignDir( envstr );
     }
 
-    cfgpath.AppendDir( wxT( ".config" ) );
-#endif
-
     cfgpath.AppendDir( wxT( "kicad" ) );
 
     // Use KICAD_CONFIG_HOME to allow the user to force a specific configuration path.