Looper: Fixed compile error when enabling DEBUG_CALLBACKS

When enabling DEBUG_CALLBACKS , compiler complains
for the undeclared identifier 'fd'.
Fix by removing undeclared objects.

Change-Id: I751a9ef9d8843350105acd6a30645f897050ffa4
diff --git a/libutils/Android.bp b/libutils/Android.bp
index 4d4294b..85a0fd2 100644
--- a/libutils/Android.bp
+++ b/libutils/Android.bp
@@ -203,6 +203,7 @@
     defaults: ["libutils_impl_defaults"],
 
     cflags: [
+        "-DDEBUG_CALLBACKS=1",
         "-DDEBUG_POLL_AND_WAKE=1",
         "-DDEBUG_REFS=1",
         "-DDEBUG_TOKENIZER=1",
diff --git a/libutils/Looper.cpp b/libutils/Looper.cpp
index 402e43c..576c61d 100644
--- a/libutils/Looper.cpp
+++ b/libutils/Looper.cpp
@@ -534,7 +534,7 @@
 
 int Looper::removeSequenceNumberLocked(SequenceNumber seq) {
 #if DEBUG_CALLBACKS
-    ALOGD("%p ~ removeFd - fd=%d, seq=%u", this, fd, seq);
+    ALOGD("%p ~ removeFd - seq=%" PRIu64, this, seq);
 #endif
 
     const auto& request_it = mRequests.find(seq);