Fix typo in Windows snapshot hash

Author: catamorphism

src/snapshots.txt

@@ -4,7 +4,7 @@ S 2012-06-20 c891dec
   freebsd-x86_64 c93d3297bf68d12a55af04fecab5c1792394fcca
   linux-x86_64 eb0e614c6f463fdbf3f40953ff122eb7cd829b85
   linux-i386 6d858ef6915517135e633043115ab51d677010c5
-  winnt-i386 ffc26150a21aac3c5b023070c0e52d3c01b188c1
+  winnt-i386 ffc26150a21aac3c5b023070c0e52d3c01b1881c
 
 S 2012-06-19 de491ea
   freebsd-x86_64 b5c1080df70136bb316286e1973fa2b5734c9a01