[llvm] Implement reserveAllocationSpace for SectionMemoryManager (PR #71968)

[Graham Markall via llvm-commits]

gmarkall wrote:

Just to add, we've been using this implementation in Numba / llvmlite for a few months now:

- It appears to solve the ARM relocation overflow error
- We haven't seen any new issues introduced by it

So as far as I can tell, the implementation here seems quite robust.

https://github.com/llvm/llvm-project/pull/71968