Fix 'test_tools_smoke' from failing due to 'tools/wakeuptime'

This fixes 'test_tools_smoke' from failing on systems
running linux < 4.6 because of the wakeuptime script.
This script uses the bpf stack maps feature which is
available only for linux 4.6+. To avoid this, we skip
running it if the minimum kernel version requirement
is not met.
Signed-off-by: Sandipan Das <sandipan@linux.vnet.ibm.com>

tests/python/test_tools_smoke.py

@@ -366,6 +366,7 @@ class SmokeTests(TestCase):
     def test_vfsstat(self):
         self.run_with_duration("vfsstat.py 1 1")
 
+    @skipUnless(kernel_version_ge(4,6), "requires kernel >= 4.6")
     def test_wakeuptime(self):
         self.run_with_duration("wakeuptime.py 1")