[InlineCost] model calls to llvm.objectsize.*

Very similar to https://reviews.llvm.org/D111272. We very often can
evaluate calls to llvm.objectsize.* regardless of inlining. Don't count
calls to llvm.objectsize.* against the InlineCost when we can evaluate
the call to a constant.

Link: https://github.com/ClangBuiltLinux/linux/issues/1302

Reviewed By: manojgupta

Differential Revision: https://reviews.llvm.org/D111456