Fix UID check in vold.

The CL fixes UID check in vold.
Previously appfuse was mounted in application's namespace. For new
public version, we mount appfuse in the system process then passes
opened files to applications.

Bug: 29970149
Test: CTS
Change-Id: Icec2e626d31d978c514eb7d1954bb59ad9556c43
1 file changed