dont fail if target doesnt support mmap64

test/mmap/mmap64.c

@@ -10,6 +10,7 @@
 
 int main(int argc, char **argv)
 {
+#ifdef __NR_mmap64
 	void *ptr;
 
 	ptr = mmap64(NULL, 4096, PROT_READ|PROT_WRITE,
@@ -21,4 +22,7 @@ int main(int argc, char **argv)
 	}
 	printf("mmap returned %p\n", ptr);
 	exit(0);
+#else
+	exit(0);
+#endif
 }