include: linux: slab: kmalloc_trace undefined when compiling drivers

[Ian Cowan]

When compiling drivers (speficially drivers/pci/hotplug), I am receiving
the following modpost error for both `kmalloc_trace` and
`kmalloc_node_trace` on the staging/staging-next branch:

ERROR: modpost: "kmalloc_trace" [drivers/pci/hotplug/acpiphp_ibm.ko] undefined!

This only occurs when I have 'CONFIG_TRACING=y' in my config, and I
have traced it down to the slab header where the kmalloc_trace is
defined. It appears that when CONFIG_TRACING is set, the kmalloc_trace
and kmalloc_node_trace do not get defined by the compiler. I do not have
enough context in this area of the code base to propose a fix or to even
know if maybe it's a local compiling issue for myself. It looks like
there are a few recent commits from August that did some refactoring in this header,
and when compiling prior to that refactoring I am able to compile the
specified drivers without error.

I will mention that I am using Red Hat gcc version 12.2.1 and make version
4.3 and am on Fedora.