clang compilation fixes

exampleLink/src/exampleLink.cpp

@@ -65,12 +65,12 @@ bool ExampleLink::init()
     pvAlarm.attach(pvStructure->getSubField("alarm"));
     pvValue = static_pointer_cast<PVDoubleArray>(
         pvStructure->getScalarArrayField("value",pvDouble));
-    if(pvValue==NULL) {
+    if(!pvValue) {
         return false;
     }
     ChannelProvider::shared_pointer provider =
         getChannelProviderRegistry()->getProvider(providerName);
-    if(provider==NULL) {
+    if(!provider) {
          cout << getRecordName() << " provider "
               << providerName << " does not exist" << endl;
         return false;
@@ -97,7 +97,7 @@ bool ExampleLink::init()
     }
     getPVValue = static_pointer_cast<PVDoubleArray>(
         getPVStructure->getScalarArrayField("value",pvDouble));
-    if(getPVValue==NULL) {
+    if(!getPVValue) {
         cout << getRecordName() << " get value not  PVDoubleArray" << endl;
         return false;
     }

exampleLink/src/exampleLinkRegister.cpp

@@ -70,8 +70,8 @@ static void exampleLinkCallFunc(const iocshArgBuf *args)
     char *providerName = args[1].sval;
     char *channelName = args[2].sval;
     ExampleLinkPtr record = ExampleLink::create(recordName,providerName,channelName);
-    if(record!=NULL) 
-    result = master->addRecord(record);
+    if(record) 
+        result = master->addRecord(record);
     if(!result) cout << "recordname" << " not added" << endl;
 }