commit 1a1beb3ab1279f83d411e96d7b5abbf7875c7956
Author: Jason Merrill <jason@redhat.com>
Date:   Thu Sep 15 12:30:03 2016 -0400

            * c-common.c (check_cxx_fundamental_alignment_constraints): Check
            DECL_EXTERNAL.

diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 57b6671..fc25686 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -7870,7 +7870,7 @@ check_cxx_fundamental_alignment_constraints (tree node,
 
   if (VAR_P (node))
     {
-      if (TREE_STATIC (node))
+      if (TREE_STATIC (node) || DECL_EXTERNAL (node))
 	/* For file scope variables and static members, the target supports
 	   alignments that are at most MAX_OFILE_ALIGNMENT.  */
 	max_align = MAX_OFILE_ALIGNMENT;