MINOR: htx: Be sure to xfer all headers in one time in htx_xfer_blks()

In the function htx_xfer_blks(), we take care to transfer all headers in one
time. When the current block is a start-line, we check if there is enough space
to transfer all headers too. If not, and if the destination is empty, a parsing
error is reported on the source.

The H2 multiplexer is the only one to use this function. When a parsing error is
reported during the transfer, the flag CS_FL_EOI is also set on the conn_stream.
diff --git a/src/mux_h2.c b/src/mux_h2.c
index ddaa751..55c7619 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -5406,8 +5406,11 @@
 
 		htx_xfer_blks(buf_htx, h2s_htx, count, HTX_BLK_EOM);
 
-		if (h2s_htx->flags & HTX_FL_PARSING_ERROR)
+		if (h2s_htx->flags & HTX_FL_PARSING_ERROR) {
 			buf_htx->flags |= HTX_FL_PARSING_ERROR;
+			if (htx_is_empty(buf_htx))
+				cs->flags |= CS_FL_EOI;
+		}
 
 		buf_htx->extra = (h2s_htx->extra ? (h2s_htx->data + h2s_htx->extra) : 0);
 		htx_to_buf(buf_htx, buf);