[PATCH] futex: remove unused empty compat_exit_robust_list()

[Lukas Bulwahn <lukas.bulwahn@gmail.com>]

Commit ba31c1a48538 ("futex: Move futex exit handling into futex code")
introduced compat_exit_robust_list() with a full-fledged implementation for
CONFIG_COMPAT, and an empty-body function for !CONFIG_COMPAT.
However, compat_exit_robust_list() is only used in futex_mm_release() under
ifdef CONFIG_COMPAT.

Hence for !CONFIG_COMPAT, make CC=clang W=1 warns:

  kernel/futex.c:314:20:
    warning: unused function 'compat_exit_robust_list' [-Wunused-function]

There is no need to declare the unused empty function for !CONFIG_COMPAT.
Simply, remove it to address the -Wunused-function warning.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
---
applies cleanly on current master and next-20201113

Thomas, please pick this minor non-urgent clean-up patch.

 kernel/futex.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 00259c7e288e..c47d1015d759 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -310,8 +310,6 @@ static inline bool should_fail_futex(bool fshared)
 
 #ifdef CONFIG_COMPAT
 static void compat_exit_robust_list(struct task_struct *curr);
-#else
-static inline void compat_exit_robust_list(struct task_struct *curr) { }
 #endif
 
 /*
-- 
2.17.1