X64 implementation: Change argument to relocator to take a 64-bit delta.  Change maximum relocation info encoding length.
Review URL: http://codereview.chromium.org/146021

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2252 ce2b1a6d-e550-0410-aec6-3dcde31c8c00