Macro checkers::verify

macro_rules! verify {
    ($state:expr) => { ... };
}

Verify the state of the allocator.

This currently performs the following tests:

• Checks that each allocation has an exact corresponding deallocation, and that it happened after the allocation it relates to.
• That there are no overlapping deallocations / allocations.
• That the thread-local timeline matches.

Will be enabled in the future:

• Check that the global timeline matches (e.g. memory is sent to a different thread, where it is de-allocated).