MDEV-33161 Function pointer signature mismatch in LF_HASH

In cmake -DWITH_UBSAN=ON builds with clang but not with GCC,
-fsanitize=undefined will flag several runtime errors on
function pointer mismatch related to the lock-free hash table LF_HASH.

Let us use matching function signatures and remove function pointer
casts in order to avoid potential bugs due to undefined behaviour.

These errors could be caught at compilation time by
-Wcast-function-type-strict, which is available starting with clang-16,
but not available in any version of GCC as of now. The old GCC flag
-Wcast-function-type is enabled as part of -Wextra, but it specifically
does not catch these errors.

Reviewed by: Vladislav Vaintroub

sql/sql_test.cc

@@ -116,7 +116,7 @@ static void print_cached_tables(void)
   /* purecov: begin tested */
   puts("DB             Table                            Version  Thread  Open  Lock");
 
-  tdc_iterate(0, (my_hash_walk_action) print_cached_tables_callback, NULL, true);
+  tdc_iterate(0, print_cached_tables_callback, NULL, true);
 
   fflush(stdout);
   /* purecov: end */