[bug report] perf env: Add perf_env__cpuid, perf_env__{nr_}pmu_mappings

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Kim Phillips,

This is a semi-automatic email about new static checker warnings.

The patch 9fe8895a27a8: "perf env: Add perf_env__cpuid,
perf_env__{nr_}pmu_mappings" from Aug 17, 2021, leads to the
following Smatch complaint:

    tools/perf/util/env.c:467 perf_env__cpuid()
    error: we previously assumed 'env' could be null (see line 461)

tools/perf/util/env.c
   457  const char *perf_env__cpuid(struct perf_env *env)
   458  {
   459          int status;
   460  
   461          if (!env || !env->cpuid) { /* Assume local operation */
   462                  status = perf_env__read_cpuid(env);
   463                  if (status)
   464                          return NULL;

If env is NULL and perf_env__read_cpuid() return zero then we are
toasted.

   465          }
   466  
   467          return env->cpuid;
   468  }

A couple of the neighboring functions are written the same way.  I'm not
sure why they don't generate checker warnings.

regards,
dan carpenter