Fix compilation error found at Linux Arch

/home/anatol/sources/archpackages/dsview-git/src/DSView/DSView/pv/data/decode/annotation.cpp: In constructor ‘pv::data::decode::Annotation::Annotation(const srd_proto_data*)’:
/home/anatol/sources/archpackages/dsview-git/src/DSView/DSView/pv/data/decode/annotation.cpp:43:17: error: ‘const struct srd_proto_data_annotation’ has no member named ‘ann_class’
  _format = pda->ann_class;

DSView/pv/data/decode/annotation.cpp

@@ -40,7 +40,7 @@ Annotation::Annotation(const srd_proto_data *const pdata) :
 		(const srd_proto_data_annotation*)pdata->data;
 	assert(pda);
 
-	_format = pda->ann_class;
+	_format = pda->ann_format;
 
 	const char *const *annotations = (char**)pda->ann_text;
 	while(*annotations) {