Few new warnings have been introduced in windows build (jsonb_util.c)

Few new warnings have been introduced in windows build.

1>e:\workspace\postgresql\master\postgresql\src\backend\utils\adt\jsonb_util.c(802):
warning C4715: 'JsonbIteratorNext' : not all control paths return a
value
1>e:\workspace\postgresql\master\postgresql\src\backend\utils\adt\jsonb_util.c(1042):
warning C4715: 'JsonbDeepContains' : not all control paths return a
value
1>e:\workspace\postgresql\master\postgresql\src\backend\utils\adt\jsonb_util.c(1175):
warning C4715: 'compareJsonbScalarValue' : not all control paths
return a value

These are quite similar to what we have fixed some time back.
Attached patch fixes these warnings. I am not sure about
fix of warning in 'JsonbIteratorNext', as there is no invalid value
for JSONB processing.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com