Emit a stop point before a call expression so that debugger has some chance of...

Emit a stop point before a call expression so that debugger has some chance of getting some footing when user wants to stop at 2nd bar() in following expression when all function calls are inlined.
  = bar() + ... + bar() + ...

clang keeps track of column numbers, so we could put location entries for all subexpressions but that will significantly bloat debug info in general, but a location for call expression is helpful here.

llvm-svn: 127018