Removed explicit m_buf[0] from Msg39Request/Msg39Reply

This also fixes the sizeof/(...) versus &m_buf-this confusion which is currently
harmless but a bug in the upcoming encoding changes.

Origin: e57fb2f72c

Msg39.cpp

@@ -167,7 +167,7 @@ void Msg39::getDocIds ( UdpSlot *slot ) {
 					  &m_r->size_readSizes ,
 					  &m_r->size_whiteList,//coll ,
 					  &m_r->ptr_readSizes,
-					  m_r->m_buf );
+					  ((char*)m_r) + sizeof(*m_r) );
 
 	// sanity check
 	if ( finalSize != requestSize ) {

Msg39.h

@@ -162,7 +162,7 @@ class Msg39Request {
 	int32_t    size_whiteList;
 	//int32_t    size_coll;
 
-	char    m_buf[0];
+	// variable data comes here
 };
 
 
@@ -204,10 +204,7 @@ public:
 	int32_t   size_facetHashList;
 	int32_t   size_clusterRecs;
 
-	// . this is the "string buffer" and it is a variable size
-	// . this whole class is cast to a udp reply, so the size of "buf"
-	//   depends on the size of that udp reply
-	char       m_buf[0];
+	// variable data comes here
 };
 
 

Msg3a.cpp

@@ -774,7 +774,7 @@ bool Msg3a::gotAllShardReplies ( ) {
 					&mr->size_docIds,
 					&mr->size_clusterRecs,
 					&mr->ptr_docIds,
-					mr->m_buf ) ) {
+					((char*)mr) + sizeof(*mr) ) ) {
 			g_errno = ECORRUPTDATA;
 			m_errno = ECORRUPTDATA;
 			log("query: msg3a: Shard had error: %s",