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/h1_htx.c b/src/h1_htx.c
index 1126eca..9ce95e0 100644
--- a/src/h1_htx.c
+++ b/src/h1_htx.c
@@ -605,7 +605,7 @@
 		return 0;
 	}
 
-	dsthtx->flags |= HTX_FL_EOI; /* no more data are expected. Only EOM remains to add now */
+	dsthtx->flags |= HTX_FL_EOM; /* no more data are expected. Only EOM remains to add now */
 	if (max < sizeof(struct htx_blk) + 1 || !htx_add_endof(dsthtx, HTX_BLK_EOM))
 		return 0;