Create a TWRP Disk Usage Class to retain state about a directory and whether we should skip it in other classes like twrpTar.
Moved Get_Folder_Size to this new class.

Change-Id: If0a0220f900eb109581f2eeaf7b76e3f7d6886f1
diff --git a/Android.mk b/Android.mk
index d96e53f..85f8072 100644
--- a/Android.mk
+++ b/Android.mk
@@ -20,6 +20,7 @@
     twrp.cpp \
     fixPermissions.cpp \
     twrpTar.cpp \
+	twrpDU.cpp \
     twrpDigest.cpp \
 
 LOCAL_SRC_FILES += \