oeqa.buildperf: add method to log shell commands

Add new methods to BuildPerfTest class for running a shell
command and logging its output.

(From OE-Core rev: 8f0b11ba1266f9c650cf34d9b394d72009ee7207)

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/buildperf/base.py

@@ -112,6 +112,11 @@ class BuildPerfTest(object):
         """Actual test payload"""
         raise NotImplementedError
 
+    def log_cmd_output(self, cmd):
+        """Run a command and log it's output"""
+        with open(self.cmd_log, 'a') as fobj:
+            runCmd(cmd, stdout=fobj)
+
     def measure_cmd_resources(self, cmd, name, legend):
         """Measure system resource usage of a command"""
         def str_time_to_timedelta(strtime):