[myanmar] Use OT_NBSP instead of OT_DOTTEDCIRCLE for OT_GB

No functional change.
diff --git a/src/hb-ot-shape-complex-myanmar-machine.rl b/src/hb-ot-shape-complex-myanmar-machine.rl
index 8036e7c..9649a91 100644
--- a/src/hb-ot-shape-complex-myanmar-machine.rl
+++ b/src/hb-ot-shape-complex-myanmar-machine.rl
@@ -44,7 +44,7 @@
 D    = 19;
 D0   = 20;
 DB   = 3;
-GB   = 12;
+GB   = 11;
 H    = 4;
 IV   = 2;
 MH   = 21;