Migrate deprecated DebugLoc::get to DILocation::get

This migrates all LLVM (except Kaleidoscope and
CodeGen/StackProtector.cpp) DebugLoc::get to DILocation::get.

The CodeGen/StackProtector.cpp usage may have a nullptr Scope
and can trigger an assertion failure, so I don't migrate it.

Reviewed By: #debug-info, dblaikie

Differential Revision: https://reviews.llvm.org/D93087