[patch] Mark some tests as XFAIL/UNSUPPORTED hidden due to GCC's omission of typedefs in inheritance.

[David Blaikie <dblaikie at gmail dot com>]

gdb.cp/impl-this.exp is testing the ability to scope names within a
class and includes cases where the base class was specified via a
typedef.

Due to GCC's PR14819 these tests weren't actually testing this case -
GCC produces the same debug info regardless of whether there's a
typedef used in the base specifier.

Clang correctly produces the typedef debug info for the base type and
exposes a variety of failures/limitations in these test cases.

The attached patch updates the tests to flag these cases as
unsupported under GCC and xfail as appropriate under Clang.

Attachment: typedef_virtual_inheritance.diff
Description: Text document