[llvm] [MIR] Fix vreg flag vector memory leak (PR #112479)

[Akshat Oke via llvm-commits]

optimisan wrote:

Was about to comment to say if this is even a right fix, but bitfield would do it.

`VRegInfo *Info = new (Allocator) VRegInfo;` is the allocation site, and there doesn't appear a delete for these, nor did I catch the destructor being called for `VRegInfo`



https://github.com/llvm/llvm-project/pull/112479