mysql55: 5.5.54 -> 5.5.57 for multiple CVEs

See:
- https://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-56.html
- https://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-56.html
- https://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-55.html
- http://www.oracle.com/technetwork/security-advisory/cpujul2017-3236622.html

Fixes: CVE-2017-3635 CVE-2017-3636 CVE-2017-3641 CVE-2017-3648 CVE-2017-3651
CVE-2017-3652 CVE-2017-3653

pkgs/servers/sql/mysql/5.5.x.nix

···
 
 stdenv.mkDerivation rec {
   name = "mysql-${version}";
-  version = "5.5.54";
+  version = "5.5.57";
 
   src = fetchurl {
     url = "mirror://mysql/MySQL-5.5/${name}.tar.gz";
-    sha256 = "1f0sg72vbhavj1cbay0gyyrrw0mjcf2k0nf30zmn2h68ik7wnfr7";
+    sha256 = "113kynpfj45fffr62xack2657pds8mkhsgg77zj94ksj3qrbvhn1";
   };
 
   patches = if stdenv.isCygwin then [