[llvm] [InferAttrs] malloc-family libcalls may write `errnomem` location (PR #164382)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

On most targets, errno is not really a global; it's a thread-local variable.  So for non-baremetal targets it should be safe to assume any non-thread-local global isn't errno.

https://github.com/llvm/llvm-project/pull/164382