[platform-releng-dev] Ignore all performance results for JDT/Core

[Philippe P Mulet <philippe_mulet@xxxxxxxxxx>]

Performance results posted on *any* recent build page are completely
inconsistent, and are either exposing missing reference data, or erratic
machine behavior.
The linux results seem a bit more accurate, though the build related tests
were anormally bad in 3.0 reference, and are throwing off the conclusions.

Interestingly, we are seeing some tests where the CPU time says +10%, and
the elapsed time says -25% ! How can ?