[compiler-rt] Do not initialize the allocator on free(nullptr). (PR #74366)

[via llvm-commits]

https://github.com/ChiaHungDuan approved this pull request.

LGTM. BTW, I think this change still makes sense even without the case mentioned in the description. I may revise the description a little bit to say some logic change and then mention the potential problem in bionic. 

https://github.com/llvm/llvm-project/pull/74366