Some cleanups to recovery.

- Remove the duplicate gCurrentUI variable in recovery.cpp;
- Refactor the load/save of locale functions;
- Clean up ui_print() to get rid of 256-byte buffer limit;
- Declare ui in common.h;
- Move the typedef of Volume into roots.h.

Test: Build and boot into recovery image.

Change-Id: Ia28c116858ca754133127a5ff9c722af67ad55b7
diff --git a/install.h b/install.h
index 7f66a51..1ec01e8 100644
--- a/install.h
+++ b/install.h
@@ -20,10 +20,9 @@
 #include <string>
 #include <ziparchive/zip_archive.h>
 
-#include "common.h"
-
 enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT, INSTALL_NONE, INSTALL_SKIPPED,
         INSTALL_RETRY };
+
 // Install the package specified by root_path.  If INSTALL_SUCCESS is
 // returned and *wipe_cache is true on exit, caller should wipe the
 // cache partition.