Simplify and rename IsLoopInvariant() test.

Simplify IsLoopInvariant() test. Also rename it to IsDefinedOutOfTheLoop()
so there is no ambiguity for example whether a instruction after the loop counts
as a loop invariant. It's up to the caller to make the interpretation.

Change-Id: I999139032b0e4d815dd1e2276f2bd428cf558686
5 files changed