CS-15239 vmware:noticed nullpointer exception when we put host in maintenance mode in clustered management setup

Reviewed-By: Kelven

Changes:
- Use of class variable of type GenericSearchBuilder causes issues when multiple threads invoke this method to findCapacity
- Changing the scope of the variable to be local to these methods.
diff --git a/server/src/com/cloud/capacity/dao/CapacityDaoImpl.java b/server/src/com/cloud/capacity/dao/CapacityDaoImpl.java
index 86da5ef..d0501c5 100755
--- a/server/src/com/cloud/capacity/dao/CapacityDaoImpl.java
+++ b/server/src/com/cloud/capacity/dao/CapacityDaoImpl.java
@@ -56,7 +56,6 @@
     
     private final SearchBuilder<CapacityVO> _hostIdTypeSearch;
 	private final SearchBuilder<CapacityVO> _hostOrPoolIdSearch;
-    protected GenericSearchBuilder<CapacityVO, SummedCapacity> SummedCapacitySearch;
 	private SearchBuilder<CapacityVO> _allFieldsSearch;
     protected final StoragePoolDaoImpl _storagePoolDao = ComponentLocator.inject(StoragePoolDaoImpl.class);
 
@@ -252,7 +251,7 @@
     @Override
     public  List<SummedCapacity> findCapacityBy(Integer capacityType, Long zoneId, Long podId, Long clusterId){
     	
-    	SummedCapacitySearch = createSearchBuilder(SummedCapacity.class);
+        GenericSearchBuilder<CapacityVO, SummedCapacity> SummedCapacitySearch = createSearchBuilder(SummedCapacity.class);
     	SummedCapacitySearch.select("dcId", Func.NATIVE, SummedCapacitySearch.entity().getDataCenterId());
         SummedCapacitySearch.select("sumUsed", Func.SUM, SummedCapacitySearch.entity().getUsedCapacity());
         SummedCapacitySearch.select("sumReserved", Func.SUM, SummedCapacitySearch.entity().getReservedCapacity());
@@ -470,7 +469,7 @@
 	}
 	public List<SummedCapacity> findByClusterPodZone(Long zoneId, Long podId, Long clusterId){
 
-    	SummedCapacitySearch = createSearchBuilder(SummedCapacity.class);
+	    GenericSearchBuilder<CapacityVO, SummedCapacity> SummedCapacitySearch = createSearchBuilder(SummedCapacity.class);
         SummedCapacitySearch.select("sumUsed", Func.SUM, SummedCapacitySearch.entity().getUsedCapacity());
         SummedCapacitySearch.select("sumTotal", Func.SUM, SummedCapacitySearch.entity().getTotalCapacity());   
         SummedCapacitySearch.select("capacityType", Func.NATIVE, SummedCapacitySearch.entity().getCapacityType());                                
@@ -505,7 +504,7 @@
 	@Override
 	public List<SummedCapacity> findNonSharedStorageForClusterPodZone(Long zoneId, Long podId, Long clusterId){
 
-    	SummedCapacitySearch = createSearchBuilder(SummedCapacity.class);
+	    GenericSearchBuilder<CapacityVO, SummedCapacity> SummedCapacitySearch = createSearchBuilder(SummedCapacity.class);
         SummedCapacitySearch.select("sumUsed", Func.SUM, SummedCapacitySearch.entity().getUsedCapacity());
         SummedCapacitySearch.select("sumTotal", Func.SUM, SummedCapacitySearch.entity().getTotalCapacity());   
         SummedCapacitySearch.select("capacityType", Func.NATIVE, SummedCapacitySearch.entity().getCapacityType());