implement support for "enum class"

This adds support for the C++11 "enum class" feature.  This is
PR c++/15246.

I chose to use the existing TYPE_DECLARED_CLASS rather than introduce
a new type code.  This seemed both simple and clear to me.

I made overloading support for the new enum types strict.  This is how
it works in C++; and it didn't seem like an undue burden to keep this,
particularly because enum constants are printed symbolically by gdb.

Built and regtested on x86-64 Fedora 20.

2014-04-14  Tom Tromey  <tromey@redhat.com>

	PR c++/15246:
	* c-exp.y (type_aggregate_p): New function.
	(qualified_name, classify_inner_name): Use it.
	* c-typeprint.c (c_type_print_base): Handle TYPE_DECLARED_CLASS
	and TYPE_TARGET_TYPE of an enum type.
	* dwarf2read.c (read_enumeration_type): Set TYPE_DECLARED_CLASS on
	an enum type.
	(determine_prefix) <case DW_TAG_enumeration_type>: New case;
	handle TYPE_DECLARED_CLASS.
	* gdbtypes.c (rank_one_type): Handle TYPE_DECLARED_CLASS on enum
	types.
	* gdbtypes.h (TYPE_DECLARED_CLASS): Update comment.
	* valops.c (enum_constant_from_type): New function.
	(value_aggregate_elt): Use it.
	* cp-namespace.c (cp_lookup_nested_symbol): Handle
	TYPE_CODE_ENUM.

2014-04-14  Tom Tromey  <tromey@redhat.com>

	* gdb.cp/classes.exp (test_enums): Handle underlying type.
	* gdb.dwarf2/enum-type.exp: Add test for enum with underlying
	type.
	* gdb.cp/enum-class.exp: New file.
	* gdb.cp/enum-class.cc: New file.

gdb/cp-namespace.c

@@ -812,6 +812,7 @@ cp_lookup_nested_symbol (struct type *parent_type,
     case TYPE_CODE_STRUCT:
     case TYPE_CODE_NAMESPACE:
     case TYPE_CODE_UNION:
+    case TYPE_CODE_ENUM:
     /* NOTE: Handle modules here as well, because Fortran is re-using the C++
        specific code to lookup nested symbols in modules, by calling the
        function pointer la_lookup_symbol_nonlocal, which ends up here.  */