[Bug testsuite/62234] warnings/errors from LTO cannot be tested

[hubicka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62234

--- Comment #3 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
https://gcc.gnu.org/ml/gcc-patches/2015-04/msg01538.html has a testcase that
should be added once this is fixed.