MINOR: htx: Rename HTX_FL_EOI flag into HTX_FL_EOM

The HTX_FL_EOI flag is not well named. For now, it is not very used. But
that will change. It will replace the EOM block. Thus, it is renamed.
diff --git a/src/tcpcheck.c b/src/tcpcheck.c
index 2a83dd1..b0352ba 100644
--- a/src/tcpcheck.c
+++ b/src/tcpcheck.c
@@ -1360,7 +1360,7 @@
 		    (istlen(body) && !htx_add_data_atonce(htx, body)))
 			goto error_htx;
 
-		htx->flags |= HTX_FL_EOI; /* no more data are expected. Only EOM remains to add now */
+		htx->flags |= HTX_FL_EOM; /* no more data are expected. Only EOM remains to add now */
 		if (!htx_add_endof(htx, HTX_BLK_EOM))
 			goto error_htx;