[patch] Fix GC issue triggered by arithmetic overflow checking

[Eric Botcazou]

> 2016-10-11  Eric Botcazou  <ebotcazou@adacore.com>
> 
> 	* tree.h (build_complex_type): Add second parameter with default.
> 	* tree.c (build_complex_type): Add NAMED second parameter and adjust
> 	recursive call.  Create a TYPE_DECL only if NAMED is true.
> 	(build_common_tree_nodes): Pass true in calls to build_complex_type.

May I backport it to the 6 branch?  It fixes the bootstrap comparison failure 
on x86-64/Solaris reported under PR bootstrap/77995 (x86-64 has patterns for 
unsigned arithmetic overflow checking on the 6 branch too).

-- 
Eric Botcazou