Otherwise libraries will not be found at runtime when installing to a
path not included in the default runtime linker's path with programs
linking brotli configured via pkg-config.
* add autotools build
* separate semantic and ABI version
* extract sources.lst (used by CMake and Automake)
* share pkgconfig templates (used by CMake and Automake)
* decoder: always set `total_out`
* encoder: fix `BROTLI_ENSURE_CAPACITY` macro (no-op after preprocessor)
* decoder/encoder: refine `free_func` contract
