[commit: ghc] ghc-8.4: Bump stm submodule to 2.4.5.0 (5acecda)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : ghc-8.4
Link       : http://ghc.haskell.org/trac/ghc/changeset/5acecda09076663aaf64d0b33f228170f97c841d/ghc

>---------------------------------------------------------------

commit 5acecda09076663aaf64d0b33f228170f97c841d
Author: Ben Gamari <ben at smart-cactus.org>
Date:   Sat Feb 3 16:23:05 2018 -0500

    Bump stm submodule to 2.4.5.0


>---------------------------------------------------------------

5acecda09076663aaf64d0b33f228170f97c841d
 libraries/stm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libraries/stm b/libraries/stm
index 8194700..5ea70d4 160000
--- a/libraries/stm
+++ b/libraries/stm
@@ -1 +1 @@
-Subproject commit 819470093eccb81d058408076df8903e781f551c
+Subproject commit 5ea70d4e15d461888866796a164bf9c177a1e8b8