perf tools: Rename perf_session_env to perf_env

As it is not necessarily tied to a perf.data file and needs using in
places where a perf_session is not required.

Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1440755289-30939-4-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 9b53b65..396e496 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -66,7 +66,7 @@
 int perf_file_header__read(struct perf_file_header *header,
 			   struct perf_header *ph, int fd);
 
-struct perf_session_env {
+struct perf_env {
 	char			*hostname;
 	char			*os_release;
 	char			*version;
@@ -98,7 +98,7 @@
 	u64				data_size;
 	u64				feat_offset;
 	DECLARE_BITMAP(adds_features, HEADER_FEAT_BITS);
-	struct perf_session_env 	env;
+	struct perf_env 	env;
 };
 
 struct perf_evlist;