Refactor DIBuilder dbg intrinsic insertion, NFC

Both dbg.declare and dbg.value insertion had duplicate code for the two
overloads with different insertion point conventions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314839 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed