dataloader/incfs openWrite returns int

Plus minor refactors

BUG: 150470163
Test: atest PackageManagerShellCommandIncrementalTest
Change-Id: Ib3a1c7c45a4abaab793be73213545ce91c98510b
Merged-In: Ib3a1c7c45a4abaab793be73213545ce91c98510b
3 files changed