Add print capture variables for pblock

[dhcdht]

before: Imp: 0x10a451d40 Signature: void ^();

after: Imp: 0x10a451d40 Signature: void ^() Variables : { <ViewController: 0x7fdd9b204060> <AppDelegate: 0x60c00002acc0> };

[dhcdht]

@kastiglione hi, I have added some comments for max_var_count. max_var_count is the number of placeholders for the variables captured by the block.

the related code

#define BLOCK_VARIABLES_COUNT ($variables_count)
struct Block_literal_1 {
    ...
    // imported variables
    Class *variables[BLOCK_VARIABLES_COUNT];
}

[filip-doordash]

I think this is super useful! Is this something that is still in progress? If not, I'd be happy to take a stab at the implementation myself.