[libpng10/el6] (4 commits) ...Update to 1.0.57 (fixed CVE-2011-3026 buffer overrun bug)

[Paul Howarth]

Summary of changes:

  850f197... Update to 1.0.56 (*)
  c49cf98... Add new CVE references: CVE-2011-2690/CVE-2011-2691/CVE-201 (*)
  e340f00... rebuilt for gcc 4.7 (*)
  8591bc8... Update to 1.0.57 (fixed CVE-2011-3026 buffer overrun bug) (*)

(*) This commit already existed in another branch; no separate mail sent