MDEV-4186 Test case main.myisampack fails on ppc32 (only)

fix the declaration to use the correct type for st_handler_check_param::sort_buffer_length.
remove redundant casts.

include/myisamchk.h

@@ -138,9 +138,9 @@ typedef struct st_handler_check_param
   /* Following is used to check if rows are visible */
   ulonglong max_trid, max_found_trid;
   ulonglong not_visible_rows_found;
+  ulonglong sort_buffer_length;
   ulonglong use_buffers;                        /* Used as param to getopt() */
-  size_t read_buffer_length, write_buffer_length;
-  size_t sort_buffer_length, sort_key_blocks;
+  size_t read_buffer_length, write_buffer_length, sort_key_blocks;
   time_t backup_time;                           /* To sign backup files */
   ulong rec_per_key_part[HA_MAX_KEY_SEG * HA_MAX_POSSIBLE_KEY];
   double new_rec_per_key_part[HA_MAX_KEY_SEG * HA_MAX_POSSIBLE_KEY];

storage/myisam/ha_myisam.cc

@@ -77,7 +77,7 @@ static MYSQL_THDVAR_ULONG(repair_threads, PLUGIN_VAR_RQCMDARG,
 static MYSQL_THDVAR_ULONGLONG(sort_buffer_size, PLUGIN_VAR_RQCMDARG,
   "The buffer that is allocated when sorting the index when doing "
   "a REPAIR or when creating indexes with CREATE INDEX or ALTER TABLE", NULL, NULL,
-  8192 * 1024, (long) (MIN_SORT_BUFFER + MALLOC_OVERHEAD), SIZE_T_MAX, 1);
+  8192 * 1024, MIN_SORT_BUFFER + MALLOC_OVERHEAD, SIZE_T_MAX, 1);
 
 static MYSQL_SYSVAR_BOOL(use_mmap, opt_myisam_use_mmap, PLUGIN_VAR_NOCMDARG,
   "Use memory mapping for reading and writing MyISAM tables", NULL, NULL, FALSE);

storage/myisam/myisamchk.c

@@ -284,25 +284,25 @@ static struct my_option my_long_options[] =
   { "read_buffer_size", OPT_READ_BUFFER_SIZE, "",
     &check_param.read_buffer_length,
     &check_param.read_buffer_length, 0, GET_ULONG, REQUIRED_ARG,
-    (long) READ_BUFFER_INIT, (long) MALLOC_OVERHEAD,
-    INT_MAX32, (long) MALLOC_OVERHEAD, (long) 1L, 0},
+    READ_BUFFER_INIT, MALLOC_OVERHEAD,
+    INT_MAX32, MALLOC_OVERHEAD, 1L, 0},
   { "write_buffer_size", OPT_WRITE_BUFFER_SIZE, "",
     &check_param.write_buffer_length,
     &check_param.write_buffer_length, 0, GET_ULONG, REQUIRED_ARG,
-    (long) READ_BUFFER_INIT, (long) MALLOC_OVERHEAD,
-    INT_MAX32, (long) MALLOC_OVERHEAD, (long) 1L, 0},
+    READ_BUFFER_INIT, MALLOC_OVERHEAD,
+    INT_MAX32, MALLOC_OVERHEAD, 1L, 0},
   { "sort_buffer_size", OPT_SORT_BUFFER_SIZE,
     "Deprecated. myisam_sort_buffer_size alias is being used",
     &check_param.sort_buffer_length,
     &check_param.sort_buffer_length, 0, GET_ULL, REQUIRED_ARG,
-    (long) SORT_BUFFER_INIT, (long) (MIN_SORT_BUFFER + MALLOC_OVERHEAD),
-    SIZE_T_MAX, (long) MALLOC_OVERHEAD, (long) 1L, 0},
+    SORT_BUFFER_INIT, MIN_SORT_BUFFER + MALLOC_OVERHEAD,
+    SIZE_T_MAX, MALLOC_OVERHEAD, 1L, 0},
   { "myisam_sort_buffer_size", OPT_SORT_BUFFER_SIZE, 
     "Alias of sort_buffer_size parameter",
     &check_param.sort_buffer_length,
     &check_param.sort_buffer_length, 0, GET_ULL, REQUIRED_ARG,
-    (long) SORT_BUFFER_INIT, (long) (MIN_SORT_BUFFER + MALLOC_OVERHEAD),
-    SIZE_T_MAX, (long) MALLOC_OVERHEAD, (long) 1L, 0},
+    SORT_BUFFER_INIT, MIN_SORT_BUFFER + MALLOC_OVERHEAD,
+    SIZE_T_MAX, MALLOC_OVERHEAD, 1L, 0},
   { "sort_key_blocks", OPT_SORT_KEY_BLOCKS, "",
     &check_param.sort_key_blocks,
     &check_param.sort_key_blocks, 0, GET_ULONG, REQUIRED_ARG,