Storage scan

[mattwildermuth]

No description provided.

[mattwildermuth]

I made two decisions in the build code that I'd appreciate feedback on:

1. I decided to make a new static library for this code to allow easier access to the recovery ui class. Originally, I wrote the storage_scan.cpp code in recovery_utils/roots.cpp; however, recovery_utils is (seemingly) intentionally not dependent on librecovery_ui, which storage_scanner.cpp relies on, because the ui code is device-specific. I got that impression from lines 53-54 and 77-81 of recovery_utils/Android.bp. Is this an ideal location for the storage scanner code? I could also instead include the storage scanner code in a different recovery library, but the scanner code did not seem to fit conceptually well with the other recovery code.

2. The other major build choice was to make librecovery_diagnostics statically linked. I decided to do so because most of the recovery libraries in librecovery_defaults are statically linked. Is this acceptable, or should librecovery_diagnostics be a shared library?