RFR: 8217445: [JVMCI] incorrect management of JVMCI compilation failure reason string

[Doug Simon]

The CompileTask::_failure_reason field assumes it is only ever assigned a compile-time constant string value (i.e. never needs to be freed). This is not the case when the value is derived from a JVMCI exception message. This patch adds support for managing a C heap allocated value in this field.

https://bugs.openjdk.java.net/browse/JDK-8217445
http://cr.openjdk.java.net/~dnsimon/8217445

-Doug