s390/vdso: Drop unused '-s' flag from KBUILD_AFLAGS_64

When clang's -Qunused-arguments is dropped from KBUILD_CPPFLAGS, it
warns:

  clang-16: error: argument unused during compilation: '-s' [-Werror,-Wunused-command-line-argument]

The compiler's '-s' flag is a linking option (it is passed along to the
linker directly), which means it does nothing when the linker is not
invoked by the compiler. The kernel builds all .o files with '-c', which
stops the compilation pipeline before linking, so '-s' can be safely
dropped from KBUILD_AFLAGS_64.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

arch/s390/kernel/vdso64/Makefile

@@ -22,7 +22,7 @@ KBUILD_AFLAGS += -DBUILD_VDSO
 KBUILD_CFLAGS += -DBUILD_VDSO -DDISABLE_BRANCH_PROFILING
 
 KBUILD_AFLAGS_64 := $(filter-out -m64,$(KBUILD_AFLAGS))
-KBUILD_AFLAGS_64 += -m64 -s
+KBUILD_AFLAGS_64 += -m64
 
 KBUILD_CFLAGS_64 := $(filter-out -m64,$(KBUILD_CFLAGS))
 KBUILD_CFLAGS_64 += -m64 -fPIC -shared -fno-common -fno-builtin