Index: mmap.c
===================================================================
--- mmap.c	(revision 194055)
+++ mmap.c	(working copy)
@@ -49,6 +49,10 @@
 #define MAP_ANONYMOUS MAP_ANON
 #endif
 
+#ifndef HAVE_SYNC_FUNCTIONS
+#define HAVE_SYNC_FUNCTIONS 0
+#endif
+
 /* A list of free memory blocks.  */
 
 struct backtrace_freelist_struct
@@ -96,7 +100,7 @@
      using mmap.  __sync_lock_test_and_set returns the old state of
      the lock, so we have acquired it if it returns 0.  */
 
-  if (!__sync_lock_test_and_set (&state->lock_alloc, 1))
+  if (HAVE_SYNC_FUNCTIONS && !__sync_lock_test_and_set (&state->lock_alloc, 1))
     {
       for (pp = &state->freelist; *pp != NULL; pp = &(*pp)->next)
 	{
@@ -158,7 +162,7 @@
      If we can't acquire the lock, just leak the memory.
      __sync_lock_test_and_set returns the old state of the lock, so we
      have acquired it if it returns 0.  */
-  if (!__sync_lock_test_and_set (&state->lock_alloc, 1))
+  if (HAVE_SYNC_FUNCTIONS && !__sync_lock_test_and_set (&state->lock_alloc, 1))
     {
       backtrace_free_locked (state, addr, size);