[commit: ghc] master: Bump stm submodule (7a73a1c)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/7a73a1cdf1c6dfa87f3a54a0576b36677af8d9d8/ghc

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

commit 7a73a1cdf1c6dfa87f3a54a0576b36677af8d9d8
Author: Ben Gamari <ben at smart-cactus.org>
Date:   Tue Nov 21 23:00:13 2017 -0500

    Bump stm submodule


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

7a73a1cdf1c6dfa87f3a54a0576b36677af8d9d8
 libraries/stm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libraries/stm b/libraries/stm
index d65fd4d..8194700 160000
--- a/libraries/stm
+++ b/libraries/stm
@@ -1 +1 @@
-Subproject commit d65fd4de49635a1e53405fe6699b46363a9d134e
+Subproject commit 819470093eccb81d058408076df8903e781f551c