ioc: getArrayValue() size output buffer based on final_type only

Handle some incorrectly defined dbChannel, to at least not crash.

getArrayValue sized the read buffer from dbChannelFinalFieldSize, but dbGet
writes dbValueSize(final_type) bytes per element — MAX_STRING_SIZE for a
DBR_STRING request, regardless of the field's own size — so a DBF_STRING field
with field_size < MAX_STRING_SIZE (synApps scalcout PAA..PLL) overflowed the
heap. Size by dbValueSize(final_type): unchanged for numeric fields and
type-changing filters (dbValueSize == field_size there), MAX_STRING_SIZE for
strings.

Author: physwkim

ioc/iocsource.cpp

@@ -121,7 +121,7 @@ void getArrayValue(dbChannel* pChannel,
                          Value& value)
 {
     auto final_type(dbChannelFinalFieldType(pChannel));
-    auto buf(std::make_shared<std::vector<char>>(dbChannelFinalElements(pChannel) * dbChannelFinalFieldSize(pChannel)));
+    auto buf(std::make_shared<std::vector<char>>(dbChannelFinalElements(pChannel) * dbValueSize(final_type)));
     long nReq = dbChannelFinalElements(pChannel);
 
     DBErrorMessage dbErrorMessage(dbChannelGet(pChannel, final_type,