RFR 8049696: com/sun/jdi/RunToExit fails with "ConnectException: Connection refused"

[Jaroslav Bachorik]

Please, review the following test change

Issue : https://bugs.openjdk.java.net/browse/JDK-8049696
Webrev: http://cr.openjdk.java.net/~jbachorik/8049696/webrev.00

The test seems to fail due to a premature attempt to connect the 
debugee. The test is trying to guard against this by monitoring the 
debugee's stdout and allowing to proceed to connect only if something 
has already arrived on stdout (presumably the "Listening for transport 
dt_socket" message). However, it does not wait for the whole message to 
be present in stdout and this might contribute to the instability.

The proposed fix replaces the arbitrary code used to launch the debugee 
with the test library ProcessTools.startProcess() and waits for the 
whole message being read from stdout before proceeding. If, for any 
reason, synchronizing on the presence of this message is still not 
enough, the call to method AttachingConnector.attach() is retried if it 
has lead to ConnectException (probably not initialized debugee).

Thanks,

-JB-