perf lock: Provide a host_env for session new

perf lock: Provide a host_env for session new

When "perf lock con" is run in a live mode, with no data file, a host
environment must be provided. Testing missed this as a failing assert
was creating the 1 line of expected stderr output.

  $ sudo perf lock con -ab true
  perf: util/session.c:195: __perf_session__new: Assertion `host_env != NULL' failed.
  Aborted

Fixes: 525a599badeeafba ("perf env: Remove global perf_env")
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>