ScanBatch.isNewSchema() returns wrong result for map datatype

isNewSchema() method checks if top-level schema or any of the deeper map schemas has changed. The last one doesn't work properly with count function.
"deeperSchemaChanged" equals true even when two map strings have the same children fields.

Discovered while trying to fix DRILL-2385.

Dataset test.json for reproducing (MAP<REQUIRED> datatype object):

{"oooi":{"oa":{"oab":{"oabc":1}}}}

Example of query:

select count(t.oooi) from dfs.tmp.`test.json` t