Remove variable name clashes in TAB_REMOVE

Remove variable name clashes in TAB_REMOVE

If foo[i] or bar[i_index] are used in TAB_REMOVE / TAB_FIND, they will
use another variable with local scope declared inside the macro.

for (int i = 0; i < 1; i++) {
    TAB_REMOVE( count, array, foo[i] );
}

will expand to:

for (int i = 0; i < 1; i++) {
    int i_index;
    .....
    for (int i = 0; i < count; i++)
        if (array[i] == foo[i])
        {
            index = i;
            break;
        }
    .....
}

And inner scope i is used to index foo, instead of the outer scope i
which we would expect without knowing the content of the macro.