Build failures due to missing 'posix_timer_event'

[Guenter Roeck <linux@roeck-us.net>]

avr32:allnoconfig:

kernel/built-in.o: In function `do_adjtimex':
(.text+0x1d748): undefined reference to `posix_timer_event'
make[1]: *** [vmlinux] Error 1

metag:allnoconfig:

kernel/built-in.o: In function `alarm_handle_timer':
alarmtimer.c:(.text.alarm_handle_timer+0x38): undefined reference to `posix_timer_event'

openrisc:allnoconfig:

kernel/built-in.o: In function `alarm_handle_timer':
alarmtimer.c:(.text+0x3fca4): undefined reference to `posix_timer_event'

unicore32:allnoconfig:

kernel/built-in.o: In function `alarm_handle_timer':
memremap.c:(.text+0x31c1c): undefined reference to `posix_timer_event'

Since I don't run allnoconfig builds for all architectures, I strongly suspect
that more are affected.

Looking into alarmtimer.c, with seems to call posix_timer_event() unconditionally,
I don't entirely understand how this can work in the first place. Maybe I am missing
something, though.

Guenter