tst_QProcess::echoTest_performance() is not an unit test but a
performance test, so moving it from 'tests/auto/corelib/io/qprocess'
to 'tests/benchmarks/corelib/io/qprocess'
Change-Id: I796788534eafc5ca3b8d86c0ec46998285fd4b8f
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>
