This method is used for accumulation of long values: if
the key does not exist, one is created. If one already exists,
the passed value is added to the previous value.
This method is similar to the existing
SparseDoubleArray.incrementValue() method
Bug: 215427055
Test: atest FrameworksCoreTests:SparseLongArrayTest
Change-Id: I771d9bc2bdd12ca4260b20186ced70f5862b6f56