This test is a strip down version of a function inside the
amalgamated sqlite source. When converted to IR clang produces
a phi instruction without debug location.
It is a continuation of D47097 focusing on a different problem
of similar structure.
This was found while investigating instructions with missing DebugLoc
after running SROA on the amalgamated sqlite source, in an attempt to
try and preserve as much debug information as possible during the
early stage passes.