[PATCH][gdb/build] Fix build with gcc 4.8.5

[Tom de Vries <tdevries@suse.de>]

Hi,

When building gdb with gcc 4.8.5, we run into problems due to unconditionally
using:
...
     gdb_static_assert (std::is_trivially_copyable<packed>::value);
...
in gdbsupport/packed.h.

Fix this by guarding the usage with HAVE_IS_TRIVIALLY_COPYABLE.

Tested by doing a full gdb build with gcc 4.8.5.

Any comments?

Thanks,
- Tom

[gdb/build] Fix build with gcc 4.8.5

---
 gdbsupport/packed.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/gdbsupport/packed.h b/gdbsupport/packed.h
index ebc66c0cb1a..cd331b5477d 100644
--- a/gdbsupport/packed.h
+++ b/gdbsupport/packed.h
@@ -18,6 +18,8 @@
 #ifndef PACKED_H
 #define PACKED_H
 
+#include "traits.h"
+
 /* Each instantiation and full specialization of the packed template
    defines a type that behaves like a given scalar type, but that has
    byte alignment, and, may optionally have a smaller size than the
@@ -38,7 +40,9 @@ struct packed
     gdb_static_assert (alignof (packed) == 1);
 
     /* Make sure packed can be wrapped with std::atomic.  */
+#if HAVE_IS_TRIVIALLY_COPYABLE
     gdb_static_assert (std::is_trivially_copyable<packed>::value);
+#endif
     gdb_static_assert (std::is_copy_constructible<packed>::value);
     gdb_static_assert (std::is_move_constructible<packed>::value);
     gdb_static_assert (std::is_copy_assignable<packed>::value);