util: introduce common version() implementation and use it everywhere This also allows us to drop build.h from a ton of files, hence do so. Since we touched the #includes of those files, let's order them properly according to CODING_STYLE.

libsystemd: add sd-hwdb library This is libudev-hwdb, but decoupled from libudev and in the libsystemd style. The core code is unchanged, apart from the following minor changes: - hwdb.bin located in /**/systemd/hwdb/ take preference over the ones located in /**/udev/ - properties are stored internally in an OrderedHashmap, rather than a linked list. - a new API call allows individual properties to be queried directly, rather than iterating over them all - the iteration over properties have been moved inside the library, rather than exposing a list directly - the unused 'flags' parameter was dropped