Reset history when we reenable logging for transactional tables (safety fix)

mysql-test/r/maria2.result:
  New results
mysql-test/t/maria2.test:
  Added test case for alter table on locked maria table
mysql-test/valgrind.supp:
  Added suppression rules for warnings in libc / libld
storage/maria/ma_extra.c:
  Remove table from trnman list if we are going to drop or rename it; We don't want not existing shares in the list when we do commit!
storage/maria/ma_recovery.c:
  Ensure that info->state don't point to history event when we disable logging for a table;  This is needed as alter table will first do commit and then unlock, which would cause us to access a non existing object when we reenable logging.
  Reset history when we reenable logging (safety fix)
storage/maria/ma_state.c:
  Do less work when share->now_transactional is not set. (Safety fix)
  Added function to remove shares to be deleted from trnman->used_tables
  Added function to reset history to current context
storage/maria/ma_state.h:
  Prototypes for new function