libbpf: start v1.2 development cycle

Bump current version for new development cycle to v1.2.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20221221180049.853365-1-andrii@kernel.org


Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>