rm usage of `link_name` for most LLVM intrinsics

The Rust intrinsics no longer use wrappers for these.
migrate to marker types
heap: remove `aligned_alloc` binding

This is not available as part of the defacto standard Windows C runtime.
It should be exposed as a separate aligned allocator.
hide C memory allocation quirks

The usage of the C standard library for dynamic memory allocation is an
implementation detail and will not always be the underlying allocator.