Handle munmap over multiple VMAs

[mikusp]

Ratchet&Clank CUSA01073 allocates multiple memory areas and then tries to unmap them in one go. According to the documentation of munmap that should be allowed.

The PR merges the VMA containing the starting address with the next one until the area reaches at least the size to unmap, and then performs the unmap as before.

[raphaelthegreat]

Merging VMAs before unmap is not accurate to freebsd unfortunately and its not guaranteed to succeed unless the mapping are contiguous in physical memory as well. In addition I'm not sure if windows placeholder mechanism allows you to call VirtualFree on multiple allocations.

I recommend to follow the freebsd logic instead https://github.com/freebsd/freebsd-src/blob/aa5d3dec9df9379ab610f426e9653d1a55b254e5/sys/vm/vm_map.c#L4031
Retrieve the first VMA iterator with FindVma and iterate entries to unmap. The existing logic can be moved to an UnmapEntry function similar to freebsd that works only on a single VMA

[mikusp]

Thanks for the suggestion, I'll make the change

[ElBread3]

With many games it instead crashes at a [Debug] <Critical> memory.cpp:operator():643: Assertion Failed! Adding a mapping to already mapped region error. Don't know if this is progress or an issue with the implementation though.

[mikusp]

@raphaelthegreat @ElBread3 I've pushed a different implementation

[brad0demx]

Would it be possible for this to get a rebase? CUSA05485 boots using this PR and I heard the splash screen should be improved on 0.5.X