hfsplus: introduce KUnit tests for HFS+ string operations

hfsplus: introduce KUnit tests for HFS+ string operations

This patch implements the Kunit based set of
unit tests for HFS+ string operations. It checks
functionality of hfsplus_strcasecmp(), hfsplus_strcmp(),
hfsplus_uni2asc(), hfsplus_asc2uni(), hfsplus_hash_dentry(),
and hfsplus_compare_dentry().

./tools/testing/kunit/kunit.py run --kunitconfig ./fs/hfsplus/.kunitconfig
[14:38:05] Configuring KUnit Kernel ...
[14:38:05] Building KUnit Kernel ...
Populating config with:
$ make ARCH=um O=.kunit olddefconfig
Building with:
$ make all compile_commands.json scripts_gdb ARCH=um O=.kunit --jobs=22
[14:38:09] Starting KUnit Kernel (1/1)...
[14:38:09] ============================================================
Running tests with:
$ .kunit/linux kunit.enable=1 mem=1G console=tty kunit_shutdown=halt
[14:38:09] ============== hfsplus_unicode (27 subtests) ===============
[14:38:09] [PASSED] hfsplus_strcasecmp_test
[14:38:09] [PASSED] hfsplus_strcmp_test
[14:38:09] [PASSED] hfsplus_unicode_edge_cases_test
[14:38:09] [PASSED] hfsplus_unicode_boundary_test
[14:38:09] [PASSED] hfsplus_uni2asc_basic_test
[14:38:09] [PASSED] hfsplus_uni2asc_special_chars_test
[14:38:09] [PASSED] hfsplus_uni2asc_buffer_test
[14:38:09] [PASSED] hfsplus_uni2asc_corrupted_test
[14:38:09] [PASSED] hfsplus_uni2asc_edge_cases_test
[14:38:09] [PASSED] hfsplus_asc2uni_basic_test
[14:38:09] [PASSED] hfsplus_asc2uni_special_chars_test
[14:38:09] [PASSED] hfsplus_asc2uni_buffer_limits_test
[14:38:09] [PASSED] hfsplus_asc2uni_edge_cases_test
[14:38:09] [PASSED] hfsplus_asc2uni_decompose_test
[14:38:09] [PASSED] hfsplus_hash_dentry_basic_test
[14:38:09] [PASSED] hfsplus_hash_dentry_casefold_test
[14:38:09] [PASSED] hfsplus_hash_dentry_special_chars_test
[14:38:09] [PASSED] hfsplus_hash_dentry_decompose_test
[14:38:09] [PASSED] hfsplus_hash_dentry_consistency_test
[14:38:09] [PASSED] hfsplus_hash_dentry_edge_cases_test
[14:38:09] [PASSED] hfsplus_compare_dentry_basic_test
[14:38:09] [PASSED] hfsplus_compare_dentry_casefold_test
[14:38:09] [PASSED] hfsplus_compare_dentry_special_chars_test
[14:38:09] [PASSED] hfsplus_compare_dentry_length_test
[14:38:09] [PASSED] hfsplus_compare_dentry_decompose_test
[14:38:09] [PASSED] hfsplus_compare_dentry_edge_cases_test
[14:38:09] [PASSED] hfsplus_compare_dentry_combined_flags_test
[14:38:09] ================= [PASSED] hfsplus_unicode =================
[14:38:09] ============================================================
[14:38:09] Testing complete. Ran 27 tests: passed: 27
[14:38:09] Elapsed time: 3.875s total, 0.001s configuring, 3.707s building, 0.115s running

v2
Rework memory management model.

Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
cc: Yangtao Li <frank.li@vivo.com>
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>