do sdcard sideloading through the fuse filesystem

Make a fuse filesystem that sits on top of the selected package file
on the sdcard, so we can verify that the file contents don't change
while being read and avoid copying the file to /tmp (that is, RAM)
before verifying and installing it.

Change-Id: Ifd982aa68bfe469eda5f839042648654bf7386a1

Android.mk

@@ -38,7 +38,8 @@ LOCAL_SRC_FILES := \
     screen_ui.cpp \
     asn1_decoder.cpp \
     verifier.cpp \
-    adb_install.cpp
+    adb_install.cpp \
+    fuse_sdcard_provider.c
 
 LOCAL_MODULE := recovery