Index: head/x11-toolkits/fox17/files/patch-lib_FXAtomic.cpp
===================================================================
--- head/x11-toolkits/fox17/files/patch-lib_FXAtomic.cpp	(revision 462098)
+++ head/x11-toolkits/fox17/files/patch-lib_FXAtomic.cpp	(revision 462099)
@@ -1,11 +1,20 @@
---- lib/FXAtomic.cpp.orig	2016-11-19 22:24:23 UTC
+--- lib/FXAtomic.cpp.orig	2017-11-29 04:44:13 UTC
 +++ lib/FXAtomic.cpp
 @@ -54,7 +54,7 @@
  
  
  // New __atomic_XXX() builtins are available
 -#if ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)))
-+#if ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7))) || defined(__clang__)
++#if ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7))) || (defined(__clang__) && defined(__x86_64__))
  #define HAVE_BUILTIN_ATOMIC 1
+ #endif
+ 
+@@ -64,7 +64,7 @@
+ #endif
+ 
+ // Can we use inline-assembly
+-#if (defined(__GNUC__) || defined(__INTEL_COMPILER))
++#if (defined(__GNUC__) || defined(__INTEL_COMPILER)) || defined(__clang__)
+ #define HAVE_INLINE_ASSEMBLY 1
  #endif