Extend the valgrind suppression to cover one more code path:

==3307== Invalid read of size 1
==3307==    at 0xA8389A: mach_read_from_4 (mach0data.ic:182)
==3307==    by 0xA833E3: buf_buddy_relocate (buf0buddy.c:450)
==3307==    by 0xA8451E: buf_buddy_free_low (buf0buddy.c:619)
==3307==    by 0x999326: buf_buddy_free (buf0buddy.ic:131)
==3307==    by 0x998B66: buf_page_get_gen (buf0buf.c:2968)
==3307==    by 0x9765D4: btr_cur_open_at_rnd_pos_func (btr0cur.c:985)
==3307==    by 0x97F5EB: btr_estimate_number_of_different_key_vals (btr0cur.c:3621)
==3307==    by 0x9C8694: dict_update_statistics (dict0dict.c:4312)
==3307==    by 0x8FCF85: row_update_statistics_if_needed (row0mysql.c:933)
==3307==    by 0x8FCEF8: row_insert_for_mysql (row0mysql.c:1240)
==3307==    by 0x8E8134: ha_innobase::write_row(unsigned char*) (ha_innodb.cc:4988)
==3307==    by 0x73CE6D: handler::ha_write_row(unsigned char*) (handler.cc:4776)
==3307==    by 0x6512DC: copy_data_between_tables(TABLE*, TABLE*, List<Create_field>&, bool, unsigned int, st_order*, unsigned long long*, unsigned long long*, enum_enable_or_disable, bool) (sql_table.cc:7017)
==3307==    by 0x65E1E1: mysql_alter_table(THD*, char*, char*, st_ha_create_information*, TABLE_LIST*, Alter_info*, unsigned int, st_order*, bool) (sql_table.cc:6416)
==3307==    by 0x893920: Alter_table_statement::execute(THD*) (sql_alter.cc:106)
==3307==    by 0x5DDB3B: mysql_execute_command(THD*) (sql_parse.cc:4321)

mysql-test/valgrind.supp

@@ -876,5 +876,4 @@
    fun:buf_buddy_relocate
    fun:buf_buddy_free_low
    fun:buf_buddy_free
-   fun:buf_LRU_block_remove_hashed_page
 }