libutils: DEBUG_* modes compile forever

I've seen these fixed before, so we compile the debug modes
now.

Bug: 244325464
Test: 'm libutils_test_compile'
Change-Id: I4271909e81893ad448bc46b8a3a567a84c40f8a3
diff --git a/libutils/Looper.cpp b/libutils/Looper.cpp
index 1a3f34b..402e43c 100644
--- a/libutils/Looper.cpp
+++ b/libutils/Looper.cpp
@@ -8,10 +8,14 @@
 //#define LOG_NDEBUG 0
 
 // Debugs poll and wake interactions.
+#ifndef DEBUG_POLL_AND_WAKE
 #define DEBUG_POLL_AND_WAKE 0
+#endif
 
 // Debugs callback registration and invocation.
+#ifndef DEBUG_CALLBACKS
 #define DEBUG_CALLBACKS 0
+#endif
 
 #include <utils/Looper.h>