Remove more custom debug defines
diff --git a/src/core/lib/iomgr/ev_epollsig_linux.c b/src/core/lib/iomgr/ev_epollsig_linux.c
index 255e070..3c4ca9c 100644
--- a/src/core/lib/iomgr/ev_epollsig_linux.c
+++ b/src/core/lib/iomgr/ev_epollsig_linux.c
@@ -54,9 +54,6 @@
     gpr_log(GPR_INFO, __VA_ARGS__);         \
   }
 
-/* Uncomment the following to enable extra checks on poll_object operations */
-/* #define PO_DEBUG */
-
 static int grpc_wakeup_signal = -1;
 static bool is_grpc_wakeup_signal_initialized = false;
 
@@ -85,7 +82,7 @@
 } poll_obj_type;
 
 typedef struct poll_obj {
-#ifdef PO_DEBUG
+#ifndef NDEBUG
   poll_obj_type obj_type;
 #endif
   gpr_mu mu;
@@ -821,7 +818,7 @@
    * would be holding a lock to it anyway. */
   gpr_mu_lock(&new_fd->po.mu);
   new_fd->po.pi = NULL;
-#ifdef PO_DEBUG
+#ifndef NDEBUG
   new_fd->po.obj_type = POLL_OBJ_FD;
 #endif
 
@@ -1079,7 +1076,7 @@
   gpr_mu_init(&pollset->po.mu);
   *mu = &pollset->po.mu;
   pollset->po.pi = NULL;
-#ifdef PO_DEBUG
+#ifndef NDEBUG
   pollset->po.obj_type = POLL_OBJ_POLLSET;
 #endif
 
@@ -1416,7 +1413,7 @@
                             poll_obj_type item_type) {
   GPR_TIMER_BEGIN("add_poll_object", 0);
 
-#ifdef PO_DEBUG
+#ifndef NDEBUG
   GPR_ASSERT(item->obj_type == item_type);
   GPR_ASSERT(bag->obj_type == bag_type);
 #endif
@@ -1575,7 +1572,7 @@
   grpc_pollset_set *pss = gpr_malloc(sizeof(*pss));
   gpr_mu_init(&pss->po.mu);
   pss->po.pi = NULL;
-#ifdef PO_DEBUG
+#ifndef NDEBUG
   pss->po.obj_type = POLL_OBJ_POLLSET_SET;
 #endif
   return pss;