Sort test order so that perf tests start first.

These take longer, so we want to start them earlier and let the shorter
tests fill in the gaps in scheduling.

CMakeLists.txt

@@ -90,6 +90,7 @@ enable_testing()
 
 set(TESTDIR ${CMAKE_CURRENT_SOURCE_DIR}/src/test)
 subdirlist(TEST_CATEGORIES ${TESTDIR})
+list(REVERSE TEST_CATEGORIES)
 foreach(TEST_CATEGORY ${TEST_CATEGORIES})
   subdirlist(TESTS ${TESTDIR}/${TEST_CATEGORY})
   foreach(TEST ${TESTS})