Fix #include order in snapshot-external.cc

This corrects a linter complaint.

BUG=
R=mstarzinger@chromium.org, vogelheim@chromium.org

Review URL: https://codereview.chromium.org/351643002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21947 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
MIPS: Fix comment in r21905: "Support LiveEdit."

BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/345243005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21948 ce2b1a6d-e550-0410-aec6-3dcde31c8c00