updating llvm submodule to include bitrig support

diff --git a/src/llvm b/src/llvm
index b89c3f039b61edbb077771eda2ee8a718dbec7e0..bff69076975642c64e76dbeaa53476bfa7212086 160000 (submodule)
--- a/src/llvm
+++ b/src/llvm
@@ -1 +1 @@
-Subproject commit b89c3f039b61edbb077771eda2ee8a718dbec7e0
+Subproject commit bff69076975642c64e76dbeaa53476bfa7212086