samples: task_profiler: Be explicit about python

Update these scripts to explicitly call out python version 2.  Some
distributions have started making /usr/bin/python version 3, and other
distros have expressed a desire to do the same.

Also use the

  #!/usr/bin/env python2

construct instead of an explicit path so that the user can more easily
use their own python install by just placing it earlier in the path

Jira: ZEP-1548
Change-Id: I36dccc652353ba8bd58c483dba3ce61d3643de00
Signed-off-by: David Brown <david.brown@linaro.org>

samples/legacy/task_profiler/profiler/scripts/contextswitch_parse.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python2
 
 #
 # Copyright (c) 2016 Intel Corporation.

samples/legacy/task_profiler/profiler/scripts/contextswitch_run.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python2
 
 #
 # Copyright (c) 2016 Intel Corporation.

samples/legacy/task_profiler/profiler/scripts/contextswitch_timeslice.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python2
 
 #
 # Copyright (c) 2016 Intel Corporation.

samples/legacy/task_profiler/profiler/scripts/contextswitch_totals.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python2
 
 #
 # Copyright (c) 2016 Intel Corporation.

samples/legacy/task_profiler/profiler/scripts/profile_kernel.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python2
 
 #
 # Copyright (c) 2016 Intel Corporation.

samples/legacy/task_profiler/profiler/scripts/profile_monitor.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python2
 
 #
 # Copyright (c) 2016 Intel Corporation.