[LV] Let recordVectorLoopValueForInductionCast to check if IV was created from the cast.

Summary:
It turned out to be error-prone to expect the callers to handle that - better to
leave the decision to this routine and make the required data to be explicitly
passed to the function.

This handles the case that was missed in the r322473 and fixes the assert
mentioned in PR36524.

Reviewers: dorit, mssimpso, Ayal, dcaballe

Reviewed By: dcaballe

Subscribers: Ka-Ka, hiraditya, dneilson, hsaito, llvm-commits

Differential Revision: https://reviews.llvm.org/D43812

llvm-svn: 327960