Make the test case from r329552 more portable

- when tuning for SCE debugger (default for ps4 targets), we will not emit
  the DW_AT_linkage_name, which this test needs. I explicitly set the
  debugger tuning parameter to get the attribute always.
- darwin targets did not like the "section .text.startup" fragment of
  the test. This is not actually needed for the test, so I remove it.

llvm-svn: 329555