MIPS: Updates to maintain flag --vector-ics

Port r24458 (18af11b)

Original commit message:
Experimental feature vector-ics needs some maintenance.

BUG=
R=dusan.milosavljevic@imgtec.com

Review URL: https://codereview.chromium.org/636163002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24467 ce2b1a6d-e550-0410-aec6-3dcde31c8c00