perf namespaces: Fixup the nsinfo__in_pidns() return type, its bool

When adding support for refconunt checking a cut'n'paste made this
function, that is just an accessor to a bool member of 'struct nsinfo',
return a pid_t, when that member is a boolean, fix it.

Fixes: bcaf0a97858de7ab ("perf namespaces: Add functions to access nsinfo")
Reported-by: Francesco Nigro <[e-mail]>
Reported-by: Ilan Green <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Clark Williams <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Yonatan Goldschmidt <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/namespaces.c

···
 	return RC_CHK_ACCESS(nsi)->pid;
 }
 
-pid_t nsinfo__in_pidns(const struct nsinfo  *nsi)
+bool nsinfo__in_pidns(const struct nsinfo *nsi)
 {
 	return RC_CHK_ACCESS(nsi)->in_pidns;
 }

tools/perf/util/namespaces.h

···
 pid_t nsinfo__tgid(const struct nsinfo  *nsi);
 pid_t nsinfo__nstgid(const struct nsinfo  *nsi);
 pid_t nsinfo__pid(const struct nsinfo  *nsi);
-pid_t nsinfo__in_pidns(const struct nsinfo  *nsi);
+bool nsinfo__in_pidns(const struct nsinfo  *nsi);
 void nsinfo__set_in_pidns(struct nsinfo *nsi);
 
 void nsinfo__mountns_enter(struct nsinfo *nsi, struct nscookie *nc);