Restore the broken cmake code

That way reviewers can see that it catches the error.

qa/CMakeLists.txt

diff --git a/qa/CMakeLists.txt b/qa/CMakeLists.txt
index 9904334..c0b6f4c 100644
--- a/qa/CMakeLists.txt
+++ b/qa/CMakeLists.txt
@@ -1,8 +1,6 @@
 add_test(paqa_errs)
 add_test(paqa_devs)
-if(LINK_PRIVATE_SYMBOLS)
-  add_test(paqa_dither)
-endif()
+add_test(paqa_dither)
 add_test(paqa_latency)
 
 subdirs(loopback)