Memory leaks in memtx_space_build_index and memtx_space_check_format functions.

[mkostoevr]

Bug description

The suspects do not free the allocated iterator if txn_check_singlestatement check is failed.

memtx_space_build_index:

• Iterator allocation: memtx_space.c +1241
• Return without deallocation: memtx_space.c +1254

memtx_space_check_format:

• Iterator allocation: memtx_space.c +990
• Return without deallocation: memtx_space.c +995

Rerpducer

box.cfg{memtx_use_mvcc_engine = false}

s = box.schema.space.create('s')
s:create_index('pk', {parts = {{1, 'scalar'}}})
s:create_index('sk', {unique = false, hint = true})

-- Fill spaces to invoke format check/index rebuild.
for i = 1, 10 do s:insert({i, i, i}) end

function memtx_space_build_index_leak()
    print(pcall(function()
        box.begin()
        -- The first index rebuild because of `hint` change.
        s.index.sk:alter({hint = false})
        -- The second index rebuild because of `unique` change.
        s.index.sk:alter({unique = true})
        box.commit()
    end))
    box.rollback()
end

function memtx_space_check_format_leak()
    s.index.sk:alter({parts = {{1, 'scalar'}}})
    print(pcall(function()
        box.begin()
        s:format({{'id', 'scalar'}})
        s:format({{'id', 'number'}})
        s:format({{'id', 'unsigned'}})
        box.commit()
    end))
    box.rollback()
end

memtx_space_check_format_leak()
memtx_space_build_index_leak()

os.exit()