[gdb] Handle AT_HWCAP3/AT_HWCAP4 in default_print_auxv_entry

On aarch64-linux, I run into:
...
(gdb) info auxv^M
  ...
26   AT_HWCAP2            Extension of AT_HWCAP          0x181^M
29   ???                                                 0x0^M
31   AT_EXECFN            File name of executable        0xffffffffffb9 ...
  ...
28   AT_RSEQ_ALIGN        rseq allocation alignment      32^M
0    AT_NULL              End of vector                  0x0^M
(gdb) WARNING: Unrecognized tag value: 29 ... ??? ... 0x0^M
FAIL: gdb.base/auxv.exp: info auxv on live process
...

Fix this by handling AT_HWCAP3 in default_print_auxv_entry.  Likewise for
AT_HWCAP4.

Tested on aarch64-linux.

Approved-By: Simon Marchi <simon.marchi@efficios.com>

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32590