TestTools: Don't warn about missing reference files for gtest-like tests.

AtlasTest/TestTools/share/post.sh

@@ -230,9 +230,14 @@ else
                fi
            fi
        else
-           tail $joblog
-           echo "$YELLOW post.sh> WARNING: reference output $reflog not available $RESET"
-           echo  " post.sh> Please check ${PWD}/$joblog"
+           # Don't warn for gtest tests.
+           tail -1 $joblog | grep 'PASSED .* tests' > /dev/null
+           refstat=$?
+           if [ $refstat != 0 ]; then
+             tail $joblog
+             echo "$YELLOW post.sh> WARNING: reference output $reflog not available $RESET"
+             echo  " post.sh> Please check ${PWD}/$joblog"
+           fi
        fi
    else
        tail $joblog