tick: Include ktime.h and jiffies.h in linux/tick.h

The !CONFIG_NO_HZ_COMMON stubs use ktime_add(), ktime_get() and TICK_NSEC,
but tick.h includes neither <linux/ktime.h> nor <linux/jiffies.h>. Most
configurations build only because those declarations arrive transitively.

Commit 6440966067 ("cpuset: Remove cpuset_cpu_is_isolated()") removed
<linux/cpuset.h> from <linux/sched/isolation.h>. The <linux/cpuset.h>
include chain had been satisfying these declarations before <linux/tick.h>
was parsed. Commit 8aa76aa415 ("ring-buffer: Use a housekeeping CPU to
wake up waiters") then added <linux/sched/isolation.h> to ring_buffer.c
ahead of any header which provides them. Neither change is wrong on its
own: the failure requires both and appeared in v7.0.

ARM rpc_defconfig + CONFIG_FUNCTION_TRACER fails to build:

  $ make ARCH=arm rpc_defconfig
  $ ./scripts/config -e FTRACE -e FUNCTION_TRACER
  $ make ARCH=arm olddefconfig
  $ make ARCH=arm kernel/trace/ring_buffer.o
  In file included from include/linux/sched/isolation.h:6,
                   from kernel/trace/ring_buffer.c:8:
  include/linux/tick.h: In function 'tick_nohz_get_next_hrtimer':
  include/linux/tick.h:156:9: error: implicit declaration of function
      'ktime_add'; did you mean 'size_add'?
  include/linux/tick.h:156:19: error: implicit declaration of function
      'ktime_get'; did you mean 'time_init'?
  include/linux/tick.h:156:32: error: 'TICK_NSEC' undeclared

Include the headers the file actually uses.

Fixes: 8aa76aa415 ("ring-buffer: Use a housekeeping CPU to wake up waiters")
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Assisted-by: Codex:gpt-5.6-sol
Link: https://patch.msgid.link/20260722062141.19671-1-kmehltretter@gmail.com

include/linux/tick.h

@@ -7,6 +7,8 @@
 
 #include <linux/clockchips.h>
 #include <linux/irqflags.h>
+#include <linux/jiffies.h>
+#include <linux/ktime.h>
 #include <linux/percpu.h>
 #include <linux/context_tracking_state.h>
 #include <linux/cpumask.h>