clang-cl: Evaluate arguments left-to-right in constructor call with initializer list (PR31831)

clang-cl would evaluate the arguments right-to-left (see PR), and for
non-Windows targets I suppose we only got it because we were already
emitting left-to-right in CodeGenFunction::EmitCallArgs.

Differential Revision: https://reviews.llvm.org/D29350

llvm-svn: 293732