libbpf-tools: update vfsstat for libbpf 1.0
libbpf-tools: update vfsstat for libbpf 1.0

Switch to libbpf 1.0 mode and adapt libbpf API usage accordingly.

Signed-off-by: Andrii Nakryiko <450886ab958931a1b640c5db7e55f3b50c4bb462@kernel.org>

iovisor/bcc,iovisor/bcc,iovisor/bcc,iovisor/bcc,brendangregg/bcc,brendangregg/bcc,iovisor/bcc,brendangregg/bcc,brendangregg/bcc,brendangregg/bcc