build breakage on -current (gdt.c)

[Thomas Klausner <tk%giga.or.at@localhost>]

--- gdt.o ---
/disk/6/archive/foreign/src/sys/arch/amd64/amd64/gdt.c:212:1: error: 'gdt_grow' defined but not used [-Werror=unused-function]
 gdt_grow(void)
 ^

I think during building the xen kernels.
I don't see any commit to that file.

The only caller of that function is inside

#if !defined(XEN) || defined(USER_LDT)

so perhaps the function and its declaration should be too.
 Thomas