PPD: Make Floating point NaN check more strict

ORC-629 added an extra check (part of  RecordReaderImp) disabling PPD when DoubleColumnStats min, max or sum is a non-Finite number.

However, the check is unnecessarily broad – the way stats are updated, using just sum for the check would suffice.
https://github.com/apache/orc/blob/master/java/core/src/java/org/apache/orc/impl/ColumnStatisticsImpl.java#L568