perf tools: Remove const from thread read accessors

The namespaces and comm fields of a thread are protected by rwsem and
require write access for it.  So it ended up using a cast to remove
the const qualifier.  Let's get rid of the const then.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Krister Johansen <kjlx@templeofstupid.com>
Link: http://lkml.kernel.org/r/20190527061149.168640-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index cf8375c..e97ef69 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -76,7 +76,7 @@ static inline void thread__exited(struct thread *thread)
 	thread->dead = true;
 }
 
-struct namespaces *thread__namespaces(const struct thread *thread);
+struct namespaces *thread__namespaces(struct thread *thread);
 int thread__set_namespaces(struct thread *thread, u64 timestamp,
 			   struct namespaces_event *event);
 
@@ -93,7 +93,7 @@ int thread__set_comm_from_proc(struct thread *thread);
 int thread__comm_len(struct thread *thread);
 struct comm *thread__comm(const struct thread *thread);
 struct comm *thread__exec_comm(const struct thread *thread);
-const char *thread__comm_str(const struct thread *thread);
+const char *thread__comm_str(struct thread *thread);
 int thread__insert_map(struct thread *thread, struct map *map);
 int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp, bool do_maps_clone);
 size_t thread__fprintf(struct thread *thread, FILE *fp);