Remove the -generate-dwarf-cu-ranges flag.
Rewrite a couple of testcases to cover areas that would be normally
by turning it on into testcases that will follow the logic.
If we see that we're emitting code for a function that doesn't have
any lexical scopes then go ahead and turn on DW_AT_ranges for the
compile unit since we would be claiming to describe in the CU
a range for which we don't have information in the CU otherwise.