Uses "else if" rather than "elseif" in coroutines.lua

[EspenBerget]

There is an extra space in test_table_coroutine_contains_six_or_seven_elements function in coroutines.lua. This creates an extra if statement which lua expects to be closed, but which is not closed by an "end"-statement.

FIX: either add another "end"-statement to the function or simply remove the space.