qemu-iotests: Allow caller to disable underscore convertion for qmp

QMP command "block_set_io_throttle" expects underscores in parameters
instead of dashes: {iops,bps}_{rd,wr,max}.

Add optional argument conv_keys (defaults to True, backward compatible),
it will be used in IO throttling test case.

Reviewed-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1422586186-9925-5-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

tests/qemu-iotests/iotests.py

@@ -185,11 +185,14 @@ class VM(object):
             self._popen = None
 
     underscore_to_dash = string.maketrans('_', '-')
-    def qmp(self, cmd, **args):
+    def qmp(self, cmd, conv_keys=True, **args):
         '''Invoke a QMP command and return the result dict'''
         qmp_args = dict()
         for k in args.keys():
+            if conv_keys:
                 qmp_args[k.translate(self.underscore_to_dash)] = args[k]
+            else:
+                qmp_args[k] = args[k]
 
         return self._qmp.cmd(cmd, args=qmp_args)