[commit: ghc] master: stm: Update submodule (again) to fix build breakage (2a18019)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/2a180195f588458a77dcac859b7c793119a57784/ghc

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

commit 2a180195f588458a77dcac859b7c793119a57784
Author: Austin Seipp <austin at well-typed.com>
Date:   Mon Dec 15 11:52:34 2014 -0600

    stm: Update submodule (again) to fix build breakage
    
    Signed-off-by: Austin Seipp <austin at well-typed.com>


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

2a180195f588458a77dcac859b7c793119a57784
 libraries/stm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libraries/stm b/libraries/stm
index ed5d29d..eadf716 160000
--- a/libraries/stm
+++ b/libraries/stm
@@ -1 +1 @@
-Subproject commit ed5d29d1e8c658427728ff1d9dece2ddd3bba8e9
+Subproject commit eadf71656bb1a75e2355aee1bd07843c8bd3482a