oeqa/core/runner: Append PID in the test result folder name

It was found a case (see the bugzilla entry) where two runners were running at the same
second, creating identical test result folders, so one of them (the second runner)
was not able to create the folder because the other has already created it,
raising the following exception (many text was removed from log)

NOTE: Executing RunQueue Tasks
NOTE: Running task 1 of 2 (/home/pokybuild/yocto-autobuilder/yocto-worker/nightly-mips/build/meta/recipes-core/images/core-image-minimal.bb:do_testsdkext)
NOTE: Running task 2 of 2 (/home/pokybuild/yocto-autobuilder/yocto-worker/nightly-mips/build/meta/recipes-sato/images/core-image-sato.bb:do_testsdkext)
NOTE: recipe core-image-sato-1.0-r0: task do_testsdkext: Started
NOTE: recipe core-image-minimal-1.0-r0: task do_testsdkext: Started
.
.
The stack trace of python calls that resulted in this exception/failure was:
File: 'exec_python_func() autogenerated', lineno: 2, function: <module>
     0001:
 *** 0002:do_testsdkext(d)
     0003:
File: '/home/pokybuild/yocto-autobuilder/yocto-worker/nightly-mips/build/meta/classes/testsdk.bbclass', lineno: 188, function: do_testsdkext
     0184:
     0185:testsdkext_main[vardepsexclude] =+ "BB_ORIGENV"
     0186:
     0187:python do_testsdkext() {
 *** 0188:    testsdkext_main(d)
     0189:}
     0190:addtask testsdkext
     0191:do_testsdkext[nostamp] = "1"
     0192:
File: '/home/pokybuild/yocto-autobuilder/yocto-worker/nightly-mips/build/meta/classes/testsdk.bbclass', lineno: 171, function: testsdkext_main
     0167:        except Exception as e:
     0168:            import traceback
     0169:            bb.fatal("Loading tests failed:\n%s" % traceback.format_exc())
     0170:
 *** 0171:        result = tc.runTests()
.
.
File: '/usr/lib64/python3.5/os.py', lineno: 241, function: makedirs
     0237:            cdir = bytes(curdir, 'ASCII')
     0238:        if tail == cdir:           # xxx/newdir/. exists if xxx/newdir exists
     0239:            return
     0240:    try:
 *** 0241:        mkdir(name, mode)
     0242:    except OSError:
     0243:        # Cannot rely on checking for EEXIST, since the operating system
     0244:        # could give priority to other errors like EACCES or EROFS
     0245:        if not exist_ok or not path.isdir(name):
Exception: FileExistsError: [Errno 17] File exists: '/home/pokybuild/yocto-autobuilder/yocto-worker/nightly-mips/build/build/TestResults_20170409130114'

[YOCTO #11318]

(From OE-Core rev: 10aa09d39c1b70ce2a88f59601f1f8dbc96ed817)

Signed-off-by: Leonardo Sandoval <leonardo.sandoval.gonzalez@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/core/runner.py

@@ -52,7 +52,7 @@ class OETestRunner(_TestRunner):
         if xmlEnabled:
             if not kwargs.get('output'):
                 kwargs['output'] = os.path.join(os.getcwd(),
-                        'TestResults_%s' % time.strftime("%Y%m%d%H%M%S"))
+                        'TestResults_%s_%s' % (time.strftime("%Y%m%d%H%M%S"), os.getpid()))
 
         super(OETestRunner, self).__init__(*args, **kwargs)
         self.tc = tc