installd: fix build-error

These were introduced by ag/10417175(use std::optional for AIDL
@nullable in C++)  because some part of code was guarded by macro
ENABLE_STORAGE_CRATES.

Bug: 150584011
Test: m (after ag/10467569, which enables ENABLE_STORAGE_CRATES)
Change-Id: Ia2d7d9ff57381ffe99779649ff572fbbe1044e10