XFAIL support for LLNL/openmp5.0-tests tests

The test test_imperfect_loop.cxx contains a loop collapse operation that
cannot be executed safely in parallel, so should be marked as expected
to fail, somehow.  This patch adds a basic way to do that.

bin/rocm-test/scripts/parse_LLNL.sh

@@ -26,6 +26,9 @@ fi
 if [ -e failing-tests.txt ]; then
   rm failing-tests.txt
 fi
+if [ -e xfail-tests.txt ]; then
+  rm xfail-tests.txt
+fi
 if [ -e make-fail.txt ]; then
   rm make-fail.txt
 fi
@@ -49,6 +52,10 @@ function parse(){
       fi
       [[ "$line" =~ $testname_regex ]]
       llnltest=${BASH_REMATCH[1]}
+      if [ "$outfile" = "failing-tests.txt" ] && \
+	 grep -Fq "$llnltest" xfail-list then
+        outfile="xfail-tests.txt"
+      fi
       echo "$llnltest" >> $outfile
     fi
   done < "$infile"

test/LLNL/openmp5.0-tests/xfail-list

@@ -0,0 +1 @@
+test_imperfect_loop run