[all] Fix uninitialized class members

era/restore_emitter.cc

@@ -14,6 +14,7 @@ namespace {
 			: md_(md),
 			  in_superblock_(false),
 			  in_writeset_(false),
+			  era_(0),
 			  in_era_array_(false) {
 		}
 

thin-provisioning/metadata_dumper.cc

@@ -645,6 +645,10 @@ namespace {
 	public:
 		mapping_emit_visitor(emitter::ptr e)
 			: e_(e),
+			  origin_start_(0),
+			  dest_start_(0),
+			  time_(0),
+			  len_(0),
 			  in_range_(false) {
 		}
 

thin-provisioning/thin_delta.cc

@@ -214,7 +214,9 @@ namespace {
 	class simple_emitter : public diff_emitter {
 	public:
 		simple_emitter(indented_stream &out)
-		: diff_emitter(out) {
+		: diff_emitter(out),
+		  vbegin_(0),
+		  vend_(0) {
 		}
 
 		void left_only(uint64_t vbegin, uint64_t dbegin, uint64_t len) {