[InlineCost] Move the code in isGEPOffsetConstant to a lambda.

Differential revision: https://reviews.llvm.org/D30112

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296208 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed