[IR] Set name when inserting 'llvm::Value*'

Summary:
I noticed a small regression in a toy project of mine after applying
D73835, in which instruction names weren't being set properly. In the
example test case included with this patch,
`llvm::IRBuilderBase::CreateAdd` returns an `llvm::Value *` that is then
passed as an argument to `llvm::IRBuilderBase::Insert`. The overloaded
function that is selected for that call then ignores the `Name`
parameter that is given. This patch addresses that issue.

Reviewers: nikic, Meinersbur, nhaehnle, fhahn, thakis, teemperor

Reviewed By: nikic, fhahn

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74754