codetag: avoid unused alloc_tags sections/symbols

With CONFIG_MEM_ALLOC_PROFILING=n, vmlinux and all modules unnecessarily
contain the symbols __start_alloc_tags and __stop_alloc_tags, which define
an empty range.  In the case of modules, the presence of these symbols
also forces the linker to create an empty .codetag.alloc_tags section.

Update codetag.lds.h to make the data conditional on
CONFIG_MEM_ALLOC_PROFILING.

Link: https://lkml.kernel.org/r/20250618125037.53182-1-petr.pavlu@suse.com


Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Casey Chen <cachen@purestorage.com>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>