Implement API dumper

sysprop_api_dump reads .sysprop files and produces a single .txt file
containing all of the signatures. It is written in TextFormat, and its
fields are sorted in lexicographical order to make the output
normalized.

Bug: 131637873
Test: mma && manually run the binary
Change-Id: Icf5e86bac89609afcaca8c29926beef8fa412d85
2 files changed