bpf: fix build when CONFIG_DEBUG_INFO_BTF[_MODULES] is undefined

Kernel test robot reports that kernel build fails with
resilient split BTF changes.

Examining the associated config and code we see that
btf_relocate_id() is defined under CONFIG_DEBUG_INFO_BTF_MODULES.
Moving it outside the #ifdef solves the issue.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202406221742.d2srFLVI-lkp@intel.com/Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/r/20240623135224.27981-1-alan.maguire@oracle.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

kernel/bpf/btf.c

@@ -6185,8 +6185,6 @@ struct btf *btf_parse_vmlinux(void)
 	return btf;
 }
 
-#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
-
 /* If .BTF_ids section was created with distilled base BTF, both base and
  * split BTF ids will need to be mapped to actual base/split ids for
  * BTF now that it has been relocated.
@@ -6198,6 +6196,8 @@ static __u32 btf_relocate_id(const struct btf *btf, __u32 id)
 	return btf->base_id_map[id];
 }
 
+#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+
 static struct btf *btf_parse_module(const char *module_name, const void *data,
 				    unsigned int data_size, void *base_data,
 				    unsigned int base_data_size)