Ensure UNSUPPORTED tests in tree-prof do not report absolute paths.

The test infrastructure for gcc.dg/tree-prof reports relative paths
for all test outcomes except UNSUPPORTED, for which it reports the
absolute path of the test case.  This patch ensure a relative path is
reported consistently reducing noise in regression test comparisons.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@208514 138bc75d-0d04-0410-961f-82ee72b054a4