EmitRecord* API change: accepts ArrayRef instead of a SmallVector (NFC)

This reapply a variant commit r247179 after post-commit review from
D.Blaikie.
Hopefully I got it right this time: lifetime of initializer list ends
as with any expression, which make invalid the pattern:

ArrayRef<int> Arr = { 1, 2, 3, 4};

Just like StringRef, ArrayRef shouldn't be used to initialize local
variable but only as function argument.

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@247233 91177308-0d34-0410-b5e6-96231b3b80d8