arm64/vdso: Remove --hash-style=sysv

glibc added support for .gnu.hash in 2006 and .hash has been obsoleted
for more than one decade in many Linux distributions.  Using
--hash-style=sysv might imply unaddressed issues and confuse readers.

Just drop the option and rely on the linker default, which is likely
"both", or "gnu" when the distribution really wants to eliminate sysv
hash overhead.

Similar to commit 6b7e2654 ("x86/vdso: Emit a GNU hash").
Signed-off-by: Fangrui Song <maskray@google.com>
Link: https://lore.kernel.org/r/20240718173423.1574395-1-maskray@google.comSigned-off-by: Will Deacon <will@kernel.org>

arch/arm64/kernel/vdso/Makefile

@@ -21,7 +21,7 @@ btildflags-$(CONFIG_ARM64_BTI_KERNEL) += -z force-bti
 # potential future proofing if we end up with internal calls to the exported
 # routines, as x86 does (see 6f121e548f83 ("x86, vdso: Reimplement vdso.so
 # preparation in build-time C")).
-ldflags-y := -shared -soname=linux-vdso.so.1 --hash-style=sysv	\
+ldflags-y := -shared -soname=linux-vdso.so.1 \
 	     -Bsymbolic --build-id=sha1 -n $(btildflags-y)
 
 ifdef CONFIG_LD_ORPHAN_WARN

arch/arm64/kernel/vdso32/Makefile

@@ -98,7 +98,7 @@ VDSO_AFLAGS += -D__ASSEMBLY__
 # From arm vDSO Makefile
 VDSO_LDFLAGS += -Bsymbolic --no-undefined -soname=linux-vdso.so.1
 VDSO_LDFLAGS += -z max-page-size=4096 -z common-page-size=4096
-VDSO_LDFLAGS += -shared --hash-style=sysv --build-id=sha1
+VDSO_LDFLAGS += -shared --build-id=sha1
 VDSO_LDFLAGS += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)