Rockbox as an application: add get_user_file_path().

For RaaA it evaluates user paths at runtime. For everything but codecs/plugins it will give the path under $HOME/.config/rockbox.org if write access is needed or if the file/folder in question exists there (otherwise it gives /usr/local/share/rockbox).
This allows for installing themes under $HOME as well as having config.cfg and other important files there while installing the application (and default themes) under /usr/local.

On the DAPs it's a no-op, returing /.rockbox directly.

Not converted to use get_user_file_path() are plugins themselves, because RaaA doesn't build plugins yet.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27656 a1c6a512-1295-4272-9138-f99709370657

firmware/common/unicode.c

@@ -27,16 +27,16 @@
  */
 
 #include <stdio.h>
+#include "config.h"
 #include "file.h"
 #include "debug.h"
 #include "rbunicode.h"
-#include "config.h"
+#include "rbpaths.h"
 
 #ifndef O_BINARY
 #define O_BINARY 0
 #endif
 
-#define CODEPAGE_DIR    ROCKBOX_DIR"/codepages"
 static int default_codepage = 0;
 static int loaded_cp_table = 0;