Some tests cause MSAN alarms due to uninitialized Item_func::not_null_tables_cache

$ LD_LIBRARY_PATH="$HOME"/msan-libs ./mtr main.subselect_sj

<...>

mysqltest: At line 80: query 'explain extended

select * from t1 left join t2 on (t2.a= t1.a and t2.a in (select pk from t10))' failed: 2013: Lost connection to MySQL server during query

Server [mysqld.1 - pid: 42990, winpid: 42990, exit: 256] failed during test run

Server log from this test:

----------SERVER LOG START-----------

$ /home/oleg/server/build/sql/mariadbd --defaults-group-suffix=.1 --defaults-file=/home/oleg/server/build/mysql-test/var/my.cnf --log-output=file --core-file --loose-debug-sync-timeout=300

<...>

Version: '10.5.25-MariaDB-debug-log'  socket: '/home/oleg/server/build/mysql-test/var/tmp/mysqld.1.sock'  port: 16000  Source distribution

==42991==WARNING: MemorySanitizer: use-of-uninitialized-value

    #0 0x5611105e3d91 in Item_func::not_null_tables() const /home/oleg/server/sql/item_func.cc:632:3

    #1 0x56111057e436 in Item_cond::fix_fields(THD*, Item**) /home/oleg/server/sql/item_cmpfunc.cc:5001:38

    #2 0x56110fd0d314 in add_cond_and_fix(THD*, Item**, Item*) /home/oleg/server/sql/sql_select.cc:11318:12

    #3 0x56110fd0d314 in make_join_select(JOIN*, SQL_SELECT*, Item*) /home/oleg/server/sql/sql_select.cc:12314:13

    #4 0x56110fce0032 in JOIN::optimize_stage2() /home/oleg/server/sql/sql_select.cc:2663:7

    #5 0x56110fce9277 in JOIN::optimize_inner() /home/oleg/server/sql/sql_select.cc:2412:9

    #6 0x56110fcdd3c1 in JOIN::optimize() /home/oleg/server/sql/sql_select.cc:1740:10

    #7 0x56110fcc7577 in mysql_select(THD*, TABLE_LIST*, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) /home/oleg/server/sql/sql_select.cc:4868:19

    #8 0x56110fdb7ec9 in mysql_explain_union(THD*, st_select_lex_unit*, select_result*) /home/oleg/server/sql/sql_select.cc:28121:10

    #9 0x56110fc3536c in execute_sqlcom_select(THD*, TABLE_LIST*) /home/oleg/server/sql/sql_parse.cc:6356:12

    #10 0x56110fc1ec65 in mysql_execute_command(THD*) /home/oleg/server/sql/sql_parse.cc:4022:12

    #11 0x56110fc0d1fb in mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool) /home/oleg/server/sql/sql_parse.cc:8196:18

    #12 0x56110fc048b3 in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool) /home/oleg/server/sql/sql_parse.cc:1891:7

    #13 0x56110fc0e50c in do_command(THD*) /home/oleg/server/sql/sql_parse.cc:1375:17

    #14 0x561110059471 in do_handle_one_connection(CONNECT*, bool) /home/oleg/server/sql/sql_connect.cc:1415:11

    #15 0x561110058fbb in handle_one_connection /home/oleg/server/sql/sql_connect.cc:1317:5

    #16 0x561110dcfab0 in pfs_spawn_thread /home/oleg/server/storage/perfschema/pfs.cc:2201:3

    #17 0x7f02f33ce133 in start_thread nptl/pthread_create.c:442:8

    #18 0x7f02f344e7db in clone3 misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

  Memory was marked as uninitialized

    #0 0x56110f88308d in __msan_allocated_memory (/home/oleg/server/build/sql/mariadbd+0x76008d) (BuildId: ef49369ab45d1225724bdc731e5cb048238867a4)

    #1 0x561111b79e06 in my_malloc /home/oleg/server/mysys/my_malloc.c:114:7

SUMMARY: MemorySanitizer: use-of-uninitialized-value /home/oleg/server/sql/item_func.cc:632:3 in Item_func::not_null_tables() const