Minor perf-related changes in FontFreeType

[j-jorge]

First commit: the blending loops were processing the bitmap column-major, but the bitmap is actually stored row-major. I've switched the loops to have a more cache-friendly iteration.

Second commit: multiple dynamic allocations were done for the bitmap buffers when using a font with an outline. This commit adds a pool of buffers to recycle for new allocations.

[halx99]

Please don't reformat full-file, refer: https://github.com/axmolengine/axmol?tab=readme-ov-file#-branches

[j-jorge]

Please don't reformat full-file, refer: https://github.com/axmolengine/axmol?tab=readme-ov-file#-branches

Done, with my apologies.

[rh101]

Multi-line blocks should be surrounded by curly brackets, such as this code in the current PR:

for (BufferPool& p : _availableBuffers)
    if (p.capacity == it->second)
    {
        p.buffers.emplace_back(buffer);
        break;
    }

should be:

for (BufferPool& p : _availableBuffers)
{
    if (p.capacity == it->second)
    {
        p.buffers.emplace_back(buffer);
        break;
    }
}

Same goes for this, where the comment block is below the conditional statement:

if ((new_pool_index == n) || (_availableBuffers[new_pool_index].capacity != size))
    // Either all pools have capacities smaller than the requested size, or else
    // We have pools with capacity larger than the requested size but none had
    // an available buffer. We create a new pool for the requested size so
    // we'll be ready to receive the buffer in releaseBuffer.
    _availableBuffers.emplace(_availableBuffers.begin() + new_pool_index)->capacity = size;

where it should be:

if ((new_pool_index == n) || (_availableBuffers[new_pool_index].capacity != size))
{
    // Either all pools have capacities smaller than the requested size, or else
    // We have pools with capacity larger than the requested size but none had
    // an available buffer. We create a new pool for the requested size so
    // we'll be ready to receive the buffer in releaseBuffer.
    _availableBuffers.emplace(_availableBuffers.begin() + new_pool_index)->capacity = size;
}