locking/static_keys: Avoid nested functions

clang does not support nested functions inside of an array definition:

  lib/test_static_keys.c:105:16: error: function definition is not allowed here
                          .test_key       = test_key_func(&old_true_key, static_key_true),
  lib/test_static_keys.c:50:20: note: expanded from macro 'test_key_func'
          ({bool func(void) { return branch(key); } func; })

That code appears to be a little too clever, so this simplifies it
a bit by defining functions outside of the array.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1454942223-2781480-1-git-send-email-arnd@arndb.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>