MIPS: Fixes for patch sites if long branches are emitted.

This resolves many mjsunit failures if long branches are forced to be emitted.

TEST=
BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/153983002

Patch from Dusan Milosavljevic <Dusan.Milosavljevic@rt-rk.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19126 ce2b1a6d-e550-0410-aec6-3dcde31c8c00