ACPICA: Avoid undefined behavior: member access within null pointer

ACPICA: Avoid undefined behavior: member access within null pointer

ACPICA commit 2411e11ef88f42b08f33c38ed9c0d40282780e8c

84449c1eef1c0d092b037dc4c2c60cec5d5cc6c4 fixed this for Linux kernel
builds, but not Linux userspace builds.

Before this change we see the following UBSAN stack trace in Fuchsia:

  ../../third_party/acpica/source/components/tables/tbfadt.c:536:39: runtime error: member access within null pointer of type 'struct acpi_table_fadt' (aka 'struct acpi_table_fadt')
      #0 0x564860b5ee9b in acpi_tb_convert_fadt ../../third_party/acpica/source/components/tables/tbfadt.c:536:39
      #1 0x564860b5edb4 in acpi_tb_create_local_fadt ../../third_party/acpica/source/components/tables/tbfadt.c:461:5
      #2 0x564860b5e5c6 in acpi_tb_parse_fadt ../../third_party/acpica/source/components/tables/tbfadt.c:371:5
      #3 0x564860b5c485 in acpi_tb_parse_root_table ../../third_party/acpica/source/components/tables/tbutils.c:407:13
      #4 0x564860b6401a in acpi_initialize_tables ../../third_party/acpica/source/components/tables/tbxface.c:160:14
      #5 0x5648608fb417 in acpi_host_test::acpi_host_test::init_acpi_with_tables(char const*) ../../src/devices/board/tests/acpi-host-tests/acpi-host-test.cc:36:5
      #6 0x5648608f9095 in acpi_host_test::acpi_host_test_device_is_child_of_scope_test_Test::test_body() ../../src/devices/board/tests/acpi-host-tests/acpi-host-test.cc:85:3
      #7 0x564860c6007e in void testing::internal::handle_seh_exceptions_in_method_if_supported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) ../../third_party/googletest/src/googletest/src/gtest.cc:2609:10
      #8 0x564860bbd5df in void testing::internal::handle_exceptions_in_method_if_supported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) ../../third_party/googletest/src/googletest/src/gtest.cc:2664:12 #9 0x564860bbd141 in testing::Test::Run() ../../third_party/googletest/src/googletest/src/gtest.cc:2684:5  #10 0x564860bbff0a in testing::test_info::Run() ../../third_party/googletest/src/googletest/src/gtest.cc:2864:11   #11 0x564860bc40f1 in testing::test_suite::Run() ../../third_party/googletest/src/googletest/src/gtest.cc:3023:30   #12 0x564860beba40 in testing::internal::unit_test_impl::run_all_tests() ../../third_party/googletest/src/googletest/src/gtest.cc:5882:44
      #13 0x564860c7db6e in bool testing::internal::handle_seh_exceptions_in_method_if_supported<testing::internal::unit_test_impl, bool>(testing::internal::unit_test_impl*, bool (testing::internal::unit_test_impl::*)(), char const*) ../../third_party/googletest/src/googletest/src/gtest.cc:2609:10
      #14 0x564860bea71f in bool testing::internal::handle_exceptions_in_method_if_supported<testing::internal::unit_test_impl, bool>(testing::internal::unit_test_impl*, bool (testing::internal::unit_test_impl::*)(), char const*) ../../third_party/googletest/src/googletest/src/gtest.cc:2664:12 #15 0x564860bea1c5 in testing::unit_test::Run() ../../third_party/googletest/src/googletest/src/gtest.cc:5456:10 #16 0x5648608fccc0 in RUN_ALL_TESTS() ../../third_party/googletest/src/googletest/include/gtest/gtest.h:2304:73 #17 0x5648608fcb7e in main ../../src/devices/board/tests/acpi-host-tests/acpi-host-test.cc:121:10 #18 0x7f6defa2d189  (/lib/x86_64-linux-gnu/libc.so.6+0x27189) (build_id: c4f6727c560b1c33527ff9e0ca0cef13a7db64d2)
      #19 0x7f6defa2d244 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x27244) (build_id: c4f6727c560b1c33527ff9e0ca0cef13a7db64d2)
      #20 0x56486082e598  (/usr/local/google/home/tamird/src/fuchsia/out/core.x64/host_x64/acpi-host-test-bin+0x359598) (build_id: 851423b0e664df6a)

Link: https://github.com/acpica/acpica/commit/2411e11e
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>