RFR: JDK-8130527: serviceability tests fails with Can't attach to process

[Alexander Kulyakhtin]

Hi,

Could you, please, review the following small test-only fix:

CR: JDK-8130527 "Serviceability tests fails with Can't attach to process." (the CR was submitted as confidential for other reasons, all changes are in the public domain)
Webrev: http://cr.openjdk.java.net/~akulyakh/8130527/index.html

Before the fix we were excluding the tests from execution based on the contents of a certain Linux file, which we read into a single String for analysis.
Due to a regression JDK-8132539 the API we used for reading the file into a string is broken.
We are changing the reading method to use an older API. 

Best regards,
Alexander