tools: Disable __packed attribute compiler warning due to -Werror=attributes

Noticed on several perf tools cross build test containers:

  [perfbuilder@five ~]$ grep FAIL ~/dm.log/summary
    19    10.18 debian:experimental-x-mips    : FAIL gcc version 12.3.0 (Debian 12.3.0-6)
    20    11.21 debian:experimental-x-mips64  : FAIL gcc version 12.3.0 (Debian 12.3.0-6)
    21    11.30 debian:experimental-x-mipsel  : FAIL gcc version 12.3.0 (Debian 12.3.0-6)
    37    12.07 ubuntu:18.04-x-arm            : FAIL gcc version 7.5.0 (Ubuntu/Linaro 7.5.0-3ubuntu1~18.04)
    42    11.91 ubuntu:18.04-x-riscv64        : FAIL gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
    44    13.17 ubuntu:18.04-x-sh4            : FAIL gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
    45    12.09 ubuntu:18.04-x-sparc64        : FAIL gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
  [perfbuilder@five ~]$

  In file included from util/intel-pt-decoder/intel-pt-pkt-decoder.c:10:
  /tmp/perf-6.6.0-rc1/tools/include/asm-generic/unaligned.h: In function 'get_unaligned_le16':
  /tmp/perf-6.6.0-rc1/tools/include/asm-generic/unaligned.h:13:29: error: packed attribute causes inefficient alignment for 'x' [-Werror=attributes]
     13 |         const struct { type x; } __packed *__pptr = (typeof(__pptr))(ptr);      \
        |                             ^
  /tmp/perf-6.6.0-rc1/tools/include/asm-generic/unaligned.h:27:28: note: in expansion of macro '__get_unaligned_t'
     27 |         return le16_to_cpu(__get_unaligned_t(__le16, p));
        |                            ^~~~~~~~~~~~~~~~~

This comes from the kernel, where the -Wattributes and -Wpacked isn't
used, -Wpacked is already disabled, do it for the attributes as well.

Fixes: a91c9872 ("perf tools: Add get_unaligned_leNN()")
Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/7c5b626c-1de9-4c12-a781-e44985b4a797@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/include/asm-generic/unaligned.h

@@ -8,6 +8,7 @@
  */
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wpacked"
+#pragma GCC diagnostic ignored "-Wattributes"
 
 #define __get_unaligned_t(type, ptr) ({						\
 	const struct { type x; } __packed *__pptr = (typeof(__pptr))(ptr);	\