Bug 1209463 - [test] Log suite names in test harnesses, r=gbrown

Suite names are currently only used by formatters to print out
an overall summary from |mach test| and |mach mochitest|. So
this doesn't need to be exact and can be tweaked further at a
later date.

If multiple test invocations have the same suite name, their
results will be merged in the overall summary. If a suite name
is missing, the summary will contain a placeholder name.

MozReview-Commit-ID: K1xpb9hUQRX

testing/runcppunittests.py

@@ -154,7 +154,7 @@ class CPPUnitTests(object):
         """
         self.xre_path = xre_path
         self.log = mozlog.get_default_logger()
-        self.log.suite_start(programs)
+        self.log.suite_start(programs, name='cppunittest')
         env = self.build_environment()
         pass_count = 0
         fail_count = 0