zdtm.py: Do not run tests marked with excl in parallel (v2)

There are tests (e.g. on locks) that can conflict with each other, so
wait for all the other jobs to finish before running such.

v2:
  Wait for the excl test to finish before launching more of them.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.py

@@ -704,10 +704,12 @@ class launcher:
 		print "=== Run %d/%d %s" % (self.__nr, self.__total, '=' * perc + '-' * (16 - perc))
 
 	def run_test(self, name, desc, flavor):
+
 		if len(self.__subs) >= self.__max:
 			self.wait()
-			if self.__fail:
-				raise test_fail_exc('')
+
+		if test_flag(desc, 'excl'):
+			self.wait_all()
 
 		self.__nr += 1
 		self.__show_progress()
@@ -720,6 +722,9 @@ class launcher:
 				stdout = open(log, "w"), stderr = subprocess.STDOUT)
 		self.__subs[sub.pid] = { 'sub': sub, 'log': log }
 
+		if test_flag(desc, 'excl'):
+			self.wait()
+
 	def __wait_one(self, flags):
 		pid, status = os.waitpid(0, flags)
 		if pid != 0:
@@ -734,15 +739,25 @@ class launcher:
 
 		return False
 
+	def __wait_all(self):
+		while self.__subs:
+			self.__wait_one(0)
+
 	def wait(self):
 		self.__wait_one(0)
 		while self.__subs:
 			if not self.__wait_one(os.WNOHANG):
 				break
+		if self.__fail:
+			raise test_fail_exc('')
+
+	def wait_all(self):
+		self.__wait_all()
+		if self.__fail:
+			raise test_fail_exc('')
 
 	def finish(self):
-		while self.__subs:
-			self.__wait_one(0)
+		self.__wait_all()
 		if self.__fail:
 			print_sep("FAIL", "#")
 			sys.exit(1)