Do not issue size error for too large array type

The error is to be issued when objects of the type are declared instead.

gcc/ada/
	* gcc-interface/decl.c (validate_size): Do not issue an error if the
	old size has overflowed.
diff --git a/gcc/ada/gcc-interface/decl.c b/gcc/ada/gcc-interface/decl.c
index 20e3eea..0120b21 100644
--- a/gcc/ada/gcc-interface/decl.c
+++ b/gcc/ada/gcc-interface/decl.c
@@ -9191,8 +9191,7 @@
   /* Issue an error either if the default size of the object isn't a constant
      or if the new size is smaller than it.  */
   if (TREE_CODE (old_size) != INTEGER_CST
-      || TREE_OVERFLOW (old_size)
-      || tree_int_cst_lt (size, old_size))
+      || (!TREE_OVERFLOW (old_size) && tree_int_cst_lt (size, old_size)))
     {
       char buf[128];
       const char *s;