For labels under one series, there were child tags created for every
data label individually.
for example, if under one series there are five labels, then under
<dLbls> there were 5 <dLbl> tags created separately.
This issue is resolved now.

Conflicts:
	chart2/qa/extras/chart2export.cxx

Change-Id: I7ae214f413bc27728df8a3d4cb8f4d703cba2f77