This commit changes the behavior of stage1 to emit libfoo.so instead
of libfoo.so.0.0.0 when none of the --ver-major, --ver-minor, or
--ver-patch flags are set.
It also makes it possible to create unversioned shared libraries
using the zig build system, changing the version parameter of
addSharedLibrary() to a tagged union.
0a76a9bd73