CSubPicQueueNoThread: Remove a useless assignment.

`ppSubPic` is assigned from `pSubPic` which itself is assigned from `m_pSubPic` so there is no reason to assign it again. Even if `m_pSubPic` was changed by another thread, it must have had a good reason to do so and we should fight for the assignment.
Subpic related classes: Correctly check for failed memory allocation.

The subtitle rendering process can be quite memory hungry and it's not really critical so we try to recover in case of failed memory allocation for one subpic. If the whole subtitle renderer fails to be allocated then we let the program error out.
Sync Renderer: Fix a typo causing the subtitle queue to be reallocated while it might not be necessary.
Sync Renderer: Add forgotten code in 15a84ec2576751bbfb49b8583fb077a43b208b12.
CSpinButtonCtrl: Use 32-bit version of the getter/setter functions.

This commit fixes #4160.